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Expanding the Class D Conversation: How Would You Characterize Their Differences?

Expanding the Class D Conversation: How Would You Characterize Their Differences?

I'm currently trialing the NAD M23 (1st gen. Eigentakt-based), and I find it intriguing enough to want to understand it better — which means understanding the broader sonic landscape of class D. So I'm crowd-sourcing.

In a recent exchange, the estimable Ralph Karsten (Atma-Sphere Music Systems) made two comments that stopped me cold. For those who missed it, here's what he said:

"IME, class D amps vary in sound more than tube amps, which is to say, quite a lot."

"IMO there is a bigger difference between various class D amps than you hear between various tube amps. IOW just because you heard one class D amp says nothing about how the next one might sound."

Link: https://forum.audiogon.com/posts/2885828

As I think through this more carefully, these are genuinely important claims. My own experience with tube amps confirms that they produce audibly distinct characters across topologies and designs. If Ralph is right and class D exceeds that range, then generalizing from one class D experience to another is even more hazardous than I assumed.

One specific question for Audiogon members:

If you have a Class D amp or have compared class D amplifiers, how would you describe their character(s)?

Here are some criteria I use:

  1. Frequency balance — Is the tonal response even across bass, mids, and treble, or does it favor certain regions?
  2. High-frequency texture — Are the highs extended and smooth, or edgy, grainy, and fatiguing?
  3. Bass definition — Is the low end tight and articulate, or loose and bloated?
  4. Midrange character — Does the midrange feel present and natural, or recessed and thin?
  5. Transient speed — Does the amp respond quickly to dynamic attacks, or does it sound sluggish and rounded?
  6. Dynamic range — Does it scale convincingly from quiet passages to loud ones, or compress the difference?
  7. Soundstage width and depth — Does it create a convincing three-dimensional image, or sound flat and narrow?
  8. Image specificity — Are instruments and voices placed precisely, or do they blur and wander?
  9. Background noise floor — Is the silence between notes actually silent, or is there grain, haze, or hash?
  10. Long-term listenability — After an extended session, do you want to keep listening, or has something been quietly fatiguing you?

If you can include relevant system context — room, speakers, preamp — please do. Those variables will help me interpret what the amp itself is contributing.

I'm less interested in rankings than in understanding what Ralph mentioned, namely the [vast] range of sonic signatures class D is capable of. Eigentakt, Hypex, Pascal, Purifi, GaN-based, etc. — all fair game.

Price is no constraint here — I'm interested in the full range of what's out there.

hilde45
atmasphere's avatar
atmasphere
12,403 posts
 

The changing o the rooms was not really a factor as regardless of the volume being played, room acoustics, etc.

@swaudiofan The sound at shows is notoriously fickle and often poor. When you hear something that sounds good it is often the exception rather than the rule. The rooms vary in size slightly from one to another so they are not a common denominator; different speakers act differently in the same room as well. In some rooms there will be side wall reflections that cause harshness and in others where directivity is more controlled the room might sound smoother, just on account of those side wall reflections alone. 

If the volume is too high, most any room at a show can be easily overpowered. That's never a good thing. 

Not all class D amps sound alike. They vary quite widely in sound; some being far more musical than others.

So a show is not a good place to draw any conclusions!!

hilde45's avatar
hilde45 OP
5,994 posts
 

@atmasphere 

Steve Guttenberg agrees with you. He said he can't make a very good judgment either. In his Best of Axpona video, he says this:

"I just want to say this right up front that for describing sound quality, well, I can't I can't do that because show conditions are less than ideal. Let's just say that. But I do get enough do get enough to know that I want to move forward with doing a review. That's the best I can offer."

decooney
2,564 posts
 

The upside to the shows, and even for people like Steve Guttenberg, they get "enough" of an idea about what they DO want to evaluate next at home.  In his last video, he rattled off a large list of speakers and components [now] on his new list to evaluate, next.  Had he not gone to Axpona, that list might not have grown so fast. People will watch the follow-up reviewers evaluating those components at home. Sure seems like a great way to get ideas. I've enjoyed Newport Beach and the Norcal shows myself. Maybe go to Axpona next year, if possible.  

Also, as commented many times by reviewers - meeting other people there, sharing ideas, pointing new things out to each other while there, I see a ton of value to the shows and it opens new doors to explore more for all.  Not able to attend, I for one appreciate the videos, sure noticed a ton of new Class A/AB, Tube systems in various rooms - as much as ever before. Still hope to read anything more posted about any of ClassD amp based systems reviewed at Axpona 2026.   

 

hilde45's avatar
hilde45 OP
5,994 posts
 

Gotta admit I'm a bit envious of Steve Guttenberg getting an idea about what to try -- for free, with no price limit on what he gets and no restocking fee. That would be cool! Nice work if you can get it...

audioguy85's avatar
audioguy85
2,049 posts
 

I'm trying class D for 1st time, I am a class A or AB guy. I have 2 NAD C268's bridged, producing 300 watts rms into 8 ohm, 500 watts  (1/2 kilowatt) on the peaks. I am thus far pretty impressed. I expected a cold overly analytical presentation, but honestly it sounds a bit on the warmer side, as well as musical. I am driving the amps with a hybrid solid state tube preanp, which I think is taming the class D a bit. 

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