OPINION
BOGGS, Circuit Judge.
On three separate occasions within an 18-month period, Simmons was arrested in possession of both crack cocaine and a firearm. He pled guilty to one count of [352]*352possession of more than five grams of crack cocaine with intent to distribute and one count of being a previously convicted felon in possession of a firearm. The district court sentenced Simmons to 116 months of imprisonment and three years of supervised release, which is within the range supplied by the advisory Sentencing Guidelines. In this appeal, Simmons contends his sentence was procedurally and substantively unreasonable. While we hold that the district court’s sentencing was adequate, the Guidelines have since been revised to lower the range for certain crack offenses and Simmons may be eligible for a sentencing reduction. Therefore we affirm and remand.
I
A federal grand jury indicted Simmons on six separate counts of firearms and narcotics offenses arising out of three separate arrests. The first arrest occurred on December 30, 2004. When officers approached his vehicle pursuant to a traffic stop, Simmons left the car, dropping a loaded handgun as he fled on foot. After arresting him, the police uncovered 3.5 grams of crack in his car. The next arrest took place roughly a year later. On February 19, 2006, police found Simmons unconscious behind the wheel of a car at an intersection. He did not have his driver’s license, and he had 5.3 grams of crack in his possession. An inventory search of his car turned up yet another loaded handgun. Simmons was prohibited from possessing a firearm because he had previously been convicted of a felony.
On February 23, 2006, a federal grand jury returned an indictment charging Simmons with two counts of being a previously convicted felon in possession of a firearm, one count of possession of crack cocaine with the intent to distribute, and one count of possession of more than five grams of crack cocaine with intent to distribute. See 18 U.S.C. § 922(g)(1); 21 U.S.C. §§ 841(a)(1) and (b)(1)(B). An arrest warrant was issued, but Simmons was not ultimately detained until May 12, 2006, in the course of still another traffic stop. On this occasion, officers found 2.9 grams of crack cocaine in his possession and retrieved a loaded 9-mm firearm from the backseat of his car. At this point, Simmons was arrested and taken into custody pursuant to the February indictment. On June 29, 2006, a federal grand jury returned a superseding indictment charging Simmons with two additional offenses in connection with his latest arrest. In total, Simmons was charged with three counts of being a convicted felon in possession of a firearm, two counts of possession with intent to distribute crack cocaine, and a single count of possession with intent to distribute more than five grams of crack cocaine.
Pursuant to a plea agreement, Simmons pled guilty to one count of being a previously convicted felon in possession of a firearm (Count 3) and one count of possession with intent to distribute over five grams of crack cocaine (Count 4). He entered this plea with full knowledge of the potential penalties. For Count 3, the statute provided for a maximum sentence of ten years of imprisonment, a fine of up to $250,000, and a three-year term of supervised release. For Count 4, the statute provided for a minimum sentence of five years of imprisonment, a maximum sentence of forty years, a maximum term of five years of supervised release, and a fine up to $2 million. At his change of plea hearing, Simmons indicated that he understood this sentence would be determined by the court, using both the Sentencing Guidelines and the factors enumerated in 18 U.S.C. § 3553(a).
[353]*353Simmons’s plea agreement expressly stated that his conduct would be considered under § 2D1.1 and § 1B1.3 of the Sentencing Guidelines. The parties also agreed to a sentencing enhancement under § 2K2.1(b)(5), which applies if a firearm was used in connection with another felony offense. The Assistant United States Attorney in turn agreed to recommend that Simmons had timely accepted responsibility for the offense. The Presentence Investigation Report found that Simmons had in his possession a total of 11.7 grams when the crack from all three drug counts was added together, which led to a base offense level of 26 for the offense in Count 4. With a two-level enhancement for the firearm and a three-level reduction for accepting responsibility, the adjusted offense level was 25. Finally, the probation officer found Simmons had 15 criminal history points, making him a Category VI offender. The advisory sentencing range was thus 110 to 137 months.
Prior to the sentencing hearing, Simmons filed a sentencing memorandum, arguing that he was entitled to a downward variance on the basis of § 3553(a). This memorandum argued that a downward variance was warranted because of the Guidelines’ disparate treatment of similar quantities of crack and powder cocaine. The government chose not to file a response, and the sentencing hearing took place on March 7, 2007. At this time, the defense again argued that the disparity in penalties for crack and powder cocaine offenses made the Guidelines range excessive and entitled the defendant to a lower sentence.
The Probation Officer recommended a sentence of 110 months, and the sentencing judge ultimately sentenced Simmons to 116 months of imprisonment and three years of supervised release. This sentence was in the lower half of the Guidelines range and, in computing the sentence, the judge referenced several of the relevant § 3553(a) factors and discussed some of the individual circumstances of the crime. In explaining the sentence, the judge did not address the Guidelines’ disparate treatment of crack and powder-cocaine offenses. At the conclusion of the proceedings, the court asked the parties whether they had any additional objections in accordance with United States v. Bostic, 371 F.3d 865 (6th Cir.2004). Defense counsel indicated that she objected to the sentence “on both procedural and substantive grounds.” The defendant now appeals the district court’s sentence, contending that it was proeedurally and substantively unreasonable.
II
Before we can determine whether the defendant’s sentence was proeedurally or substantively objectionable, we must first determine what standard of review to apply to these claims. As a general proposition, the Federal Rules of Criminal Procedure distinguish between cases in which a party objects to a court’s decision and those in which a party neglects to make an objection, despite an opportunity to do so. Fed.R.Crim.P. 51(b). This court reviews the former category of cases under a reasonableness standard and the latter category under a plain-error standard. Ibid. The application of this rule poses many difficulties in the context of sentencing proceedings because of the inherent difficulty of determining when a party has had “a meaningful opportunity to object.” Bostic, 371 F.3d at 873 n. 6.
In Bostic, we sought to clarify matters by suggesting that, after pronouncing the defendant’s sentence, the district court “ask the parties whether they have any objections to the sentence ... that have not previously been raised.” Id. at 872. [354]*354This approach not only ensures that parties may object to the court’s reasoning or failure to address a particular argument, it also affords the district court an opportunity to correct errors right away and facilitates appellate review by identifying “precisely which objections have been preserved.” Id. at 873. Indeed, it seems especially pertinent with respect to objections that concern the adequacy of the court’s explanation precisely because such objections cannot be made until after the court states its reasoning in the course of sentencing the defendant.
In United States v. Vonner, this court determined the standard of review to apply when “a sentencing judge asks this question and ... the relevant party does not object.” 516 F.3d 382, 385 (6th Cir.2008) (en banc). After pronouncing the defendant’s sentence in that case, the district court asked both parties whether they “ha[d] any objection to the sentence just pronounced.” Id. at 384. Vonner’s counsel replied, “No, Your Honor.” Ibid. On appeal, the defendant claimed for the first time that his sentence was procedurally inadequate because the district court’s pronouncement of the sentence did not address specifically defendant’s arguments for a downward variance. Vonner held that the more exacting “plain error” standard of review, not reasonableness, should apply to this objection. “No doubt, we could encourage district courts to ask the Bostic question without imposing any consequences on a party’s failure to answer it. But that would undermine its effectiveness.” Id. at 391. Vonner emphasized that substantive and procedural claims made by counsel prior to sentencing are reviewed for reasonableness, regardless of how counsel subsequently answers the Bostic question. Id. at 386 (holding defense counsel’s answer to the Bostic question “did not undermine Vonner’s right to appeal issues that he had ‘previously raised’ ”). After all, “[t]he point of the question is not to require counsel to repeat objections or, worse, to undo previously raised objections.” Id. at 390. Imposing a more exacting standard of review to any claim that has not been previously raised, however, encourages parties to give the district court one opportunity to address these arguments.
The case at bar involves a slight variation on the facts presented in Vonner, but requires only the application, not extension, of the underlying rule set forth in that case.1 Simmons’s trial counsel devot[355]*355ed much of her argument to the idea that a downward variance was warranted under 18 U.S.C. § 3553(a)(6), because of the Guidelines’ disparate treatment of crack and powder cocaine offenses. The district court failed to address this argument explicitly in sentencing the defendant. Unlike in Vonner, however, Simmons’s counsel answered the Bostic question in the affirmative, proclaiming, “Your Honor, I object just for the record for the procedural, substantive aspects.” In this appeal, Simmons repeats his claim that a within-the-Guidelines sentence for possession of crack is substantively objectionable. For the first time, the defendant also contends that the district court failed to address this substantive argument in pronouncing a within-the-Guidelines sentence and that the sentencing judge’s failure to state affirmatively that he agrees with the policies underlying the disparate treatment of crack and powder cocaine, or that he does not believe a categorical departure is warranted in this case, renders the proceeding procedurally inadequate.
In ascertaining the standard of review, we must distinguish between Simmons’s substantive and procedural objections. Defense counsel’s answer to the Bostic question is immaterial to the standard of review we apply in evaluating Simmons’s substantive argument for a below-the-Guidelines sentence under the § 3553(a) factors. After all, defense counsel clearly argued before the sentencing court that the disparate treatment of crack and powder cocaine requires a downward variance, and it is unnecessary for a party to repeat previously made objections in order to secure the lower standard of review on appeal.
The defendant makes a total of three procedural claims on appeal: (1) the district court failed to address defendant’s argument for a downward variance based on the disparate treatment of crack and powder cocaine; (2) the district court’s analysis of § 3553(a)(2) was inadequate, because the judge failed to consider whether drug treatment would be available to the defendant even if he were given a lower sentence; and (3) the district court improperly treated the Guidelines as mandatory. Br. of Appellant 13-23. The last two arguments were not raised before the district court on any reading of the record, and therefore they are subject to plain error review. See Vonner, 516 F.3d at 385. Determining what standard of review applies to Simmons’s other procedural claim poses a more complex inquiry.
Responding to the Bostic question, defense counsel objected to the “procedural ... aspeet[ ]” of the sentence just pronounced by the district court but did not allege that the sentencing judge failed to address her policy argument or specifically object to this purported failure.2 We must [356]*356determine whether defense counsel’s vague response to the Bostic question is sufficient to secure a lower standard of review for the defendant’s procedural objection, or whether a party’s answer must be specific enough to afford the district court an opportunity to address the particular claim.
To resolve this issue, we must reference the rationale for asking the Bostic question and for applying a higher standard of review to those objections that are not as a preliminary matter presented to the district court. The first goal is to help the court of appeals ascertain whether a party had an opportunity to make additional objections. Bostic, 371 F.3d at 872-73. This end is served by asking the question, no matter what the party answers. Because the record in this case makes apparent the question was asked and, accordingly, that both parties had an opportunity to make further objections, there is no need to impose a higher standard of review under these circumstances to vindicate this objective.
The second justification for the Bostic question is to ensure the district court has an opportunity to correct any error “on the spot,” id. at 873, and it would be sacrificed if a higher standard of review were not applied in cases like this one.3 Providing disincentives for parties who do not give the district court an opportunity to resolve objections helps conserve judicial resources by deterring unnecessary delay and the need to appeal. In this case, defense counsel’s response to the Bostic question may have been in the affirmative, but it was not specific enough to give the district court an opportunity to correct the alleged error. Indeed, the defense never questioned the adequacy of the court’s explanation or the court’s failure to address Simmons’s argument about the disparate treatment of crack and powder cocaine, at best leaving the sentencing judge to guess what additional objections defense counsel sought to preserve.4
[357]*357If a party need only say that he has further objections and wishes to preserve them, omitting any explanation as to what they are, the Bostic question would be a meaningless formality whereby certain magic words are uttered and any new claim may be raised on appeal without consequence. In fact, this formal interpretation would likely deprive district courts of an opportunity to correct errors by penalizing a party’s specificity: vague responses would guarantee that any new objection made on appeal will be subject to a less deferential standard of review and specific responses would result in the forfeiture of all other objections that were not explicitly made. In the alternative, it would transform the Bostic question from a single question into an interrogation, whereby the district court is obligated to badger parties into making their case or guess their objections whenever they answer in evasive, but affirmative, terms.
The third and final goal for asking the Bostic question is to create “a more reliable record” for appeal. Id. at 873. Requiring a party to detail an objection not previously made can facilitate the appellate process, and this case illustrates how. As discussed below, it is unnecessary for a sentencing judge to respond to frivolous or purely legal arguments. If Simmons’s defense counsel had made a more specific objection, the judge might have defended his decision and we, in turn, would have the benefit of his explanation in assessing the adequacy of the proceedings. The sentencing judge might have said, as we conclude is the case, that the court had already addressed the argument in a satisfactory manner. Or the judge could have chosen to obviate the issue entirely by expounding his reasons at some length. The Bostic question was intended to reduce the need for context-based inquiry by the courts of appeals into sentencing decisions,5 and the application of a higher stan[358]*358dard of review in cases like this one will discourage parties from making vague objections that deprive this court of a more complete record to review.
We hold that Vonner requires the application of plain-error review to procedural claims like this one, where a party answers the Bostic question in the affirmative, but at such a high degree of generality that the district court has no opportunity to correct its purported error and the court of appeals has been deprived of a more detailed record to review.
Ill
Sentencing determinations have both procedural and substantive components. United States v. Borho, 485 F.3d 904, 908 (6th Cir.2007). Simmons objects to his sentence on both grounds. His procedural objection about the district court’s failure to address the disparate treatment of crack and powder cocaine is reviewed for plain error,6 and the underlying substantive argument on which it is based is reviewed for reasonableness under an abuse of discretion standard. We proceed to consider each in turn.
A. Procedural Adequacy
A sentence is procedurally inadequate only if the “district judge fails to ‘consider’ the applicable Guidelines range or neglects to ‘consider’ other factors listed in 18 U.S.C. § 3553(a), and instead simply selects what the judge deems an appropriate sentence without such required consideration.” United States v. Webb, 403 F.3d 373, 383 (6th Cir.2005), cert. denied, 126 S.Ct. 1110 (2006). The district court is not required to refer explicitly to each of the statutory sentencing factors when imposing a sentence. United States v. Morris, 448 F.3d 929, 932 (6th Cir.2006). However, the district judge must “make an individualized assessment based on the facts presented,” and must discuss all relevant statutory factors to facilitate “reasonable appellate review.” Gall v. United States, 552 U.S. 38, 128 S.Ct. 586, 596-97, 169 L.Ed.2d 445 (2007); Morris, 448 F.3d at 932.
In this case, there is no question that the district judge considered the Guidelines range, that he understood the Guidelines were advisory,7 and that he con[359]*359sidered several of the § 3553(a) factors in imposing the sentence. Contrary to the defendant’s allegation that the trial judge’s entire analysis is “perfunctory” and little more than “ritualistic incantation,” Br. of Appellant 13, the court did in fact consider some of the individual circumstances of this case, referencing the defendant’s specific crimes, the defendant’s “extensive criminal history,” and the defendant’s “history of substance abuse [and his] need for substance abuse treatment.” The record strongly suggests that the sentencing judge believed these facts were the most critical elements of his decision and justified sentencing the defendant within the advisory Guidelines range.
The sentencing judge’s analysis of § 3553(a) factors is two-and-a-half pages, which is terse, but certainly not per se inadequate. At times, the trial judge uses generic language to describe the defendant’s crimes. He states the precise details of the drug and gun offenses and without elaboration characterizes the “nature and circumstances” of the offenses as “serious.” In light of the judge’s brevity, such analysis is short of ideal in assuring this court that the trial judge in fact did his full duty. On its own, however, it surely does not overcome the deference we must accord lower courts in sentencing criminal defendants. Vonner, 516 F.3d at 392 (“[District courts have considerable discretion in this area....”). The defendant makes three additional arguments in support of remand: (1) the district court’s analysis of § 3553(a)(2); (2) the district court’s analysis of § 3553(a)(6); and (3) the district court’s failure to acknowledge expressly its power to vary from the Guidelines based on policy disagreements.
1. The District Court’s Analysis of § 3553(a)(2)
The defendant contends that the district court failed to address his “cogent explanation as to why a sentence below the advisory Guidelines range satisfied Congress’ mandate in sentencing.” Br. of Appellant 21. Under § 3553(a)(2), a court must consider whether the sentence reflects the seriousness of the offense, promotes respect for the law, provides just punishment, deters similar criminal conduct, protects the public from the defendant, and provides the defendant with medical treatment or educational training. In imposing the 116-month sentence, the district court explicitly considered Simmons’s “history of substance abuse” and “need for substance abuse treatment,” the risk he poses to the public as a repeat offender “in possession of numerous firearms,” and the interest in deterring other potential drug offenders. Although the defendant claims the district court unreasonably failed to consider that Simmons is ineligible for a sentencing reduction contingent on his completion of the Federal Bureau of Prisons Drug Treatment Program, Br. of Appellant 21-22, Simmons never presented this argument to the district court, and an adequate explanation requires no such analysis. Even if correctional treatment of this variety is available to prisoners with shorter sentences, the district court might still conclude that the possibility of recidivism and the need to deter criminal conduct nevertheless make a 116-month sentence “not greater than necessary.” 18 U.S.C. § 3553(a).
[360]*3602. The District Court’s Analysis of § 3553(a)(6)
Defendant’s argument concerning the district court’s analysis of § 3553(a)(6), which provides that a judge may deviate from the advisory Guidelines range “to avoid unwarranted sentence disparities,” is stronger but still ultimately fails. A sentencing judge must explicitly consider factors that are raised by the defendant or that are otherwise especially relevant to the case at bar. United States v. (Kossie Lamon) Simmons, 501 F.3d 620, 625 (6th Cir.2007). Here, the defendant invoked § 3553(a)(6) and the court expressly considered the factor in sentencing him. The sentencing judge remarked,
[T]he Court has considered the advisory Sentencing Guidelines and the need to avoid unwarranted sentencing disparities. The defendant’s sentencing range is 110 to 137 months imprisonment. The Court has considered this advisory range in determining the appropriate sentence, and the sentence is within that range. Therefore, it is unlikely to result in unwarranted disparities.
The procedural adequacy of Simmons’s sentence hinges not on whether the district court discussed § 3553(a)(6), but on the quality of the district court’s explanation.
The record squarely indicates, and the, government in fact concedes, that defense counsel made a substantive claim regarding the Guidelines’ disparate treatment of crack and powder cocaine. Br. of Appellee 16-17 (“[T]he district court did not explicitly distinguish or reject his argument on the potential impact of the 100:1 crack to powder cocaine ratio.”). Because no corresponding procedural objection to the district court’s failure to directly address this argument was made during sentencing proceedings, the defendant must demonstrate that the district court’s omission was plain error to obtain relief. This entails proving the district court made (1) an error, (2) that was obvious or clear, (3) that affected defendant’s substantial rights, and (4) that affected the fairness, integrity, or public reputation of the judicial proceedings. United States v. Houston, 529 F.3d 743, 750 (6th Cir.2008); see also Fed.R.Crim.P. 52(b) (“A plain error that affects substantial rights may be considered even though it was not brought to the court’s attention.”).
The first step in our inquiry is to determine whether an adequate explanation of § 3553(a)(6) compelled the court to respond to Simmons’s assertion that the disparate treatment of similar quantities of crack and powder cocaine created unwarranted sentencing disparities. Even under the less onerous abuse-of-discretion standard, district courts are entitled to a great deal of deference in explaining a sentence that falls within the Guidelines. “When a district court adequately explains why it imposed a particular sentence, especially one within the advisory Guidelines range, we do not further require that it exhaustively explain the obverse — why an alternative sentence was not selected in every instance.” United States v. Gale, 468 F.3d 929 (6th Cir.2006); see also United States v. Fernandez, 443 F.3d 19, 30 (2d Cir.2006) (“[W]e will not conclude that a district judge shirked her obligation to consider the § 3553(a) factors simply because she did not ... address every argument relating to those factors that the defendant advanced.”), cert. denied, 549 U.S. 882, 127 S.Ct. 192, 166 L.Ed.2d 143 (2006).
The Second Circuit even accords “a strong presumption that the sentencing judge has considered all arguments properly presented to her, unless the record clearly suggests otherwise.” Fernandez, 443 F.3d at 29. Although we have not [361]*361adopted this position, the Supreme Court has prescribed a very deferential standard that we have adhered to. Under Rita v. United States, 551 U.S. 338, 127 S.Ct. 2456, 168 L.Ed.2d 203 (2007), “[t]he sentencing judge should set forth enough to satisfy the appellate court that he has considered the parties’ arguments and has a reasoned basis for exercising his own legal decisionmaking authority.” Id. at 2468. This explanation can be “brief,” ibid., and need only explain the court’s reasoning in a manner sufficient to permit meaningful appellate review. United States v. McGee, 494 F.3d 551, 556-57 (6th Cir.2007).
Still, our case law and the Federal Rules of Criminal Procedure indicate that, as a procedural matter, the district judge must generally speak to arguments that are clearly presented and in dispute. United States v. Gale, 468 F.3d 929 (6th Cir.2006) (“When, on appeal, a defendant’s argument and supporting evidence presents [sic] an arguably meritorious claim for a lesser sentence, but there is little to suggest that the district court actually considered it, then remand may be appropriate.”); Fed.R.Crim.P. 32(i)(3)(B) (“[T]he court must — for any disputed portion of the presentence report or other controverted matter — rule on the dispute or determine that a ruling is unnecessary either because the matter will not affect sentencing, or because the court will not consider the matter in sentencing.”). The Supreme Court has likewise held that a district court’s thorough explanation “servefs] a salutary purpose” and “can provide relevant information to both the court of appeals and ultimately to the Sentencing Commission,” which will facilitate appellate review and will “help the Guidelines constructively evolve over time, as both Congress and the Commission foresaw.” Rita, 127 S.Ct. at 2469. Once a defendant disputes a particular issue, the district court becomes obligated to find any facts that are essential to the “clarity of the record.” United States v. White, 492 F.3d 380, 415 (6th Cir.2007) (citations omitted). In White, for example, we reversed the sentencing court when it “blindly embraced the figures set forth in Defendant White’s PSR-figures” without comment. Id. at 416.
There are certain exceptions to this rule. A district court, for example, is not obligated to review defendant’s argument when it lacks any factual basis or legal merit. See United States v. Richardson, 437 F.3d 550, 554 (6th Cir.2006); Gale, 468 F.3d at 940 (“[A]rguments clearly without merit can, and for the sake of judicial economy should, be passed over in silence.”), cert. denied, 551 U.S. 1162, 127 S.Ct. 3065, 168 L.Ed.2d 758 (2007). However, Simmons’s argument regarding the disparate treatment of crack and powder cocaine does not fall within this exception, because it is a non-frivolous claim that some courts have accepted. Kimbrough v. United States, 552 U.S. 85, 128 S.Ct. 558, 169 L.Ed.2d 481 (2007) (reversing the Fourth Circuit and “[g]iving due respect to the District Court’s reasoned appraisal” that the disparate treatment of crack and powder cocaine warranted a downward variance). The sentencing disparities that result from crack and powder-cocaine convictions have engendered extensive discussion by the Sentencing Commission and, more recently, a modification of the Guidelines. 28 U.S.C. § 994(a), (p).
Another exception to the requirement of explicit discussion applies when the defendant presents issues that are “conceptually straightforward,” Vonner, 516 F.3d at 388, such that we may assume, even absent express analysis by the judge, that the sentence reflects consideration of the argument. Ibid, (holding that the [362]*362judge evidenced his consideration of an argument for a downward variance simply “by declining to give [the defendant] a lower sentence.”). The government takes this tack in characterizing the district court’s judgment as a rejection of an argument without merit that required no further explanation. “[T]he sentencing court obviously felt the most relevant factors for consideration were Simmons’s history and characteristics along with the seriousness of the offense.” Br. of Appellee 19. And by not varying downward, the judge indicated his belief that crack and powder cocaine do not necessarily warrant the same treatment.
Finally, the rule that a sentencing judge must address every disputed argument that a defendant makes generally has been read as only applying to factual disputes and not legal arguments. United States v. Cunningham, 429 F.3d 673, 678 (7th Cir.2005) (“The rule may be limited to factual disputes. The cases so assume, without so stating outright.”); United States v. Nelson, 356 F.3d 719, 722-23 (6th Cir.2004) (vacating defendant’s sentence when the “district court gave no indication as to how it calculated the loss and determined that the government’s calculations were correct [and failed to] respond to Nelson’s specific objections.”). At oral argument, the government emphasized that Simmons’s counsel at sentencing merely reiterated standard legal arguments that did not incorporate the personal characteristics of the defendant and specific circumstances of his crime, contending that the district court’s failure to grapple in explicit terms with a standard legal argument does not render his sentence procedurally inadequate.8
Although Simmons’s argument was non-frivolous, defendants convicted for possession of crack have routinely made the same underlying substantive claim, and therefore the sentencing judge was no doubt familiar with this line of reasoning. Moreover, it involved a legal, not factual, matter. Where a party makes a conceptually straightforward legal argument for a lower sentence under one of the § 3553(a) factors, the district court’s decision not to address the party’s argument expressly is not an error when the court otherwise discussed the specific factor and appears to have considered and implicitly rejected the argument. In this case, there is nothing in the record to suggest the judge did not understand defendant’s argument regarding the disparate treatment of crack and powder cocaine, as it was made repeatedly and adamantly by counsel, or recognize his ability to vary on the basis of a categorical disagreement with the crack Guidelines. The judge repeatedly observed that the Guidelines were advisory, concluding with respect to this individual defendant that sentencing disparities were less likely to result from a sentence within the Guidelines range.
The distinction between legal and factual arguments seems especially pertinent in this context, because requiring courts to respond to categorical disagreements explicitly would compel the district court to defend the underlying policies the Guidelines embody. District courts may not assume, as we do on appeal, that a sentence within the Guidelines is presumptively reasonable, Nelson, — U.S. -, 129 S.Ct. 890, 172 L.Ed.2d 719; Rita, 551 U.S. at 351, 127 S.Ct. 2456, but we may assume they considered the policies underlying the advisory range if there [363]*363is no evidence to the contrary. With respect to arguments under § 3553(a)(6), in particular, the Supreme Court has held, “avoidance of unwarranted disparities was clearly considered by the Sentencing Commission when setting the Guidelines ranges,” and the district court’s very act of correctly calculating and reviewing the advisory range indicates that a district judge “necessarily gave significant weight and consideration to the need to avoid unwarranted disparities.” Gall, 128 S.Ct. at 599.
Adequately explaining the reasons for sentencing does not require expressly defending the abstract justifications for the sentencing range. Of course, if adhering to the Guidelines were sufficient to eliminate all unwarranted sentencing disparities, then there would be no need for the independent consideration invited by § 3553(a)(6). But the substantive arguments that a district court must address involve allegations that, were the Guidelines followed, an unwarranted disparity would result because other judges have departed from the same guideline with respect to similarly situated offenders. (Kossie Lamon) Simmons, 501 F.3d at 623-24.
Here, Simmons is objecting to “the district court’s mere failure to fully explain the extent of its consideration of sentencing factors,” Houston, 529 F.3d at 751, which it appears to have fully considered. In short, this claim does not demonstrate Simmons’s sentencing was marked by “significant procedural error,” Gall, 128 S.Ct. at 597, constituting a plain error, such that remand is necessary.
3. The District Court’s Power to Depart Categorically
Simmons’s final argument relies on recent Supreme Court cases, decided after his case, and an allegation that the district judge erroneously believed he could not vary from the Guidelines on the basis of policy disagreements as opposed to the personal characteristics of the defendant or the circumstances of the crime. See Kimbrough, 552 U.S. 85, 128 S.Ct. 558, 169 L.Ed.2d 481; Moore v. United States, — U.S. -, 129 S.Ct. 4, 4, 172 L.Ed.2d 1 (2008) (“[T]he [district] court showed that it did not think it had the discretion later upheld by Kimbrough.”); Spears v. United States, — U.S. -, 129 S.Ct. 840, 172 L.Ed.2d 596 (Jan. 21, 2009) (holding that district courts may vary from the Guidelines on the basis of categorical policy disagreements with the crack Guidelines). Like Simmons’s previous procedural claims, this one is reviewed only for plain error, since it was not made before the district court.
In one of the cases defendant cites, Moore v. United States, the Supreme Court indicated that a judge commits error if he said that the court did not have the authority to depart from the Guidelines range on the basis of substantive disagreements with the Guidelines’ determinations about the seriousness of the crime. 129 S.Ct. at 4 (“[T]he [district] court showed that it did not think it had the discretion later upheld by Kimbrough.”). Moore vacated a sentence when the district court explicitly held that the disparate treatment of crack and powder cocaine is not a reasonable grounds on which to depart from the Guidelines range. We echoed this conclusion in United States v. Johnson, 553 F.3d 990 (6th Cir.2009), holding that when a district court made express statements that “the [e]ourt must apply the Guidelines,” id. at 996 n. 1 (emphasis in the original), remand was necessary “to give the district court an opportunity to impose a sentence with full recognition of its authority to reject and vary from the crack-cocaine Guidelines based solely on a policy [364]*364disagreement with those Guidelines.” Id. at 991; see also United States v. Porter, 312 Fed.Appx. 772, 775-777 (6th Cir.2009) (observing that “we did not merely assume in Johnson that the district court lacked ‘full awareness of this authority,’ but we instead relied on the district court’s express statements at the sentencing hearing” indicating it lacked the power to vary categorically based on policy disagreement).
Simmons alleges that “the [district] court [in sentencing him] ... essentially treated the 100:1 ratio as a mandatory guideline,” making his case indistinguishable from Moore and Johnson. Br. of Appellant 16. The record, however, belies the defendant’s claim. At Simmons’s sentencing, the district court observed at five separate points that the Guidelines were advisory. There is simply no indication whatsoever that the judge believed the Guidelines were mandatory, or that the court believed it was not free to vary downward based on both particularized circumstances of the crime and defendant or based on substantive disagreement with the crack Guidelines.9 Indeed, Simmons’s sentencing is different from Moore and the other cases in this line because the district court never expressly held, or even intimated, that he was not free to depart from the Guidelines on the basis of either a categorical policy disagreement or the personal circumstances of the defendant. It would be a misreading of the Supreme Court’s cases to say that a sentencing judge must explicitly recognize that such variances are permitted when the court has given no indication that it believes they are prohibited and explicitly recognizes the advisory nature of the Guidelines. Therefore we decline to accept this interpretation, and we instead hold that when a district court observes that the Guidelines are advisory and provides no indication that policy disagreements are not a proper basis to vary, then a sentence within the Guidelines range remains presumptively reasonable on appeal.
Although the defendant contends this circuit “impliedly” held district courts were not allowed to vary based on categorical disagreements, Br. of Appellant 19, we reject the defendant’s position that our law in any sense precluded downward variances of this kind or that the district court was therefore unaware of its power to categorically vary.10 Where the sentencing record is at worst ambiguous with respect to the district court’s awareness of its authority to depart, the question is not whether Simmons suffered prejudice, but whether he can even show an error.11
[365]*365Therefore we cannot say the district court’s explanation constitutes an error, let alone an error that “was obvious or clear,” affecting the defendant’s substantial rights and calling into doubt “the fairness, integrity, or public reputation of the judicial proceedings.” United States v. Gardiner, 463 F.3d 445, 459 (6th Cir.2006). We are applying, after all, a deferential standard in which sentences are reversed only in “exceptional circumstances ... where the error is so plain that the trial judge ... [was] derelict in countenancing it.” Ibid. Such is not the situation in this case, where the district court explicitly recognized the advisory nature of the Guidelines, considered all the relevant sentencing factors, including the need to avoid unwarranted sentencing disparities. The district court’s failure to speak directly to its own power to depart from the Guidelines for policy reasons does not supply a basis for inferring plain error. Nor does it warrant appellate remand.
B. Substantive Adequacy
A sentence within the Guidelines range is presumptively reasonable. Rita, 127 S.Ct. at 2459; United States v. Williams, 436 F.3d 706, 708 (6th Cir.2006). Our circuit takes a deferential approach to this type of substantive sentencing challenge. See Vonner, 516 F.3d at 392 (“[T]he central lesson [of recent Supreme Court activity is] that district courts ... deserve the benefit of the doubt when we review their sentences and the reasons given for them.”). As the Supreme Court has explained, when a sentencing judge’s determination falls within the Guidelines range, “that double determination significantly increases the likelihood that the sentence is a reasonable one.” Rita, 127 S.Ct. at 2463. There may be occasions when a sentence within the Guidelines range is substantively unreasonable. But we have held this is no small burden and that we will not generally “second guess” sentences on substantive grounds when they fall in the range prescribed by the Guidelines. United States v. Davis, 537 F.3d 611, 618 (6th Cir.2008).
Despite Simmons’s allegation, there is no evidence that the lower court selected Simmons’s sentence arbitrarily, based its determination on impermissible factors, disregarded any relevant concern, or gave unreasonable weight to any of the § 3553(a) factors. Although the district court clearly placed great weight on Simmons’s criminal history, the nature and circumstances of the offense, the need to rehabilitate Simmons, and the need to deter other potential drug offenders, the court did not weigh these factors so heavily as to make the sentence substantively unreasonable. The district court also stressed the need to avoid “unwarranted sentencing disparities” in punishing similarly situated people, and found that a sentence within the Guidelines range was likely to serve this end in this case.
For Simmons’s sentence to be substantively unreasonable, we would have [366]*366to hold not that district courts may vary from the Guidelines based on the disparate treatment of crack and powder cocaine, but that crack sentences are unreasonable unless the district judge varies from the Guidelines. Although the defendant takes for granted that the disparate treatment of crack and powder cocaine is unfair, there are reasons to punish a person in possession of crack cocaine more harshly than a person who possesses a similar quantity of powder cocaine. After all, crack is a more concentrated form of powder cocaine, is more addictive, and is associated with higher levels of crime. U.S. Sentencing Commission, Special Report to the Congress Cocaine and Federal Sentencing Policy (1995), http://www.ussc.gov/ CRACK/CHAP6.HTM. For these reasons, we have repeatedly held the disparate treatment of crack and powder cocaine advised by the Guidelines is not per se unreasonable or unconstitutional. United States v. Caver, 470 F.3d 220, 249 (6th Cir.2006) (holding “while a departure from the 100:1 ratio may well be reasonable in a particular case, applying the ratio does not, ipso facto, make a sentence unreasonable under existing case law.”); United States v. Blair, 214 F.3d 690, 702 (6th Cir.2000) (“The law is well settled in this circuit that the 100:1 ratio withstands constitutional scrutiny.”).
IV
Although we affirm the district court’s sentence for the reasons set forth above, we nevertheless remand because Simmons is entitled to a “second look” consideration pursuant 18 U.S.C. § 3582(c). On May 1, 2007, the Sentencing Commission submitted amendments to the federal Sentencing Guidelines to Congress, and they took effect on November 1, 2007. One of the amendments lowered the Guidelines range for certain crack offenses by certain offenders, providing for a downward adjustment of two levels to each threshold quantity enumerated in § 2D1.1. (The new Guidelines retain a very substantial differential.) On March 3, 2008, the amendments to the crack Guidelines were made retroactive, so that thousands of defendants serving certain sentences can file a motion for a sentence reduction. U.S.S.G. App’x C Supplement, Amendment 706 (Nov. 1, 2007) (regarding two-level reduction); U.S.S.G. App’x C Supplement, Amendment 713 (Mar. 3, 2008) (regarding retroactivity).
We have already issued a decision concerning the retroactive crack cocaine amendments, and the government does not appear to dispute that the revised Guidelines require the resentencing of certain defendants who have been convicted of possession of crack. See United States v. Poole, 538 F.3d 644, 645 (6th Cir.2008) (“The government agrees that the case should be remanded.... ”). When applicable, the proper procedure for this court to follow is to affirm the sentence and remand if the amendment would alter the Guidelines range for this particular defendant. Id. at 645; U.S.S.G. § 1B1.10(a)(2)(B) (Resentencing a defendant “is not consistent with this policy statement and therefore is not authorized under 18 U.S.C. 3582(c)(2) if’ the reduction “does not have the effect of lowering the defendant’s applicable guideline range....”). If Simmons were resentenced today, he would start out with a base offense level of 24 (more than 5 grams, but less than 20 grams of cocaine base). He would then get a two-level enhancement for a firearm, and a three-level reduction for accepting responsibility, leaving him with a total offense level of 23. The Guidelines range for a Category VI offender is 91-115 months. As a result, the two-level reduction would have the effect of lowering his guideline range from [367]*367his current range of 110-137 months, and therefore the Guidelines do not preclude application of § 3582(c).
V
For the foregoing reasons, we AFFIRM Simmons’s sentence and REMAND the case for possible consideration under the 2007 Amendments.