I've had personal experience with a handful of Class D amps and heard many more at some shows. I've always experienced the most musical result when they have been combined with tube preamps. And of course, the cables and speakers make a difference, too.
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:
- Frequency balance — Is the tonal response even across bass, mids, and treble, or does it favor certain regions?
- High-frequency texture — Are the highs extended and smooth, or edgy, grainy, and fatiguing?
- Bass definition — Is the low end tight and articulate, or loose and bloated?
- Midrange character — Does the midrange feel present and natural, or recessed and thin?
- Transient speed — Does the amp respond quickly to dynamic attacks, or does it sound sluggish and rounded?
- Dynamic range — Does it scale convincingly from quiet passages to loud ones, or compress the difference?
- Soundstage width and depth — Does it create a convincing three-dimensional image, or sound flat and narrow?
- Image specificity — Are instruments and voices placed precisely, or do they blur and wander?
- Background noise floor — Is the silence between notes actually silent, or is there grain, haze, or hash?
- 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.
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@cooperdude6 , FWIW, Rowland’s current offerings, the Daemon and Continuum 2 integrated amps, are Class D. Pascal modules, as far I understand, with, of course, Rowland & Holm magic added. |
I have the AGD Duets, the Boulder 866 and the Pass INT-25 (same design as the XA-25 but with a built in preamp). My house does not have air conditioning, so my primary motivation for getting the Duets was to have lower power amps that I can use in summer. I compared the AGD Duets and Pass INT-25 with the Songer S1x speakers. I think that any comparisons of amplifiers is going to depend on how good of a match they are for the characteristics of the speakers, so my comparison might not be relevant to others. In the thread on the Songer S1x speakers, Ken has a description of the characteristics of his speakers and the types of amps that match well with the S1x. The Duets differ from some of the other AGD amps in that they use a Gallium Nitride Power MOSFET design for both the output power stage and the power supply. I also took the Duets to YG's listening room to hear them with the Haley 3, and the Duets compared well to the much more expensive Burmester 909 monoblocks that we also listened to. I'm not a reliable reviewer - I rely mostly on whether the music is emotionally engaging, and that can be affected by a lot of other variables, like my stress and attention level. For what it's worth, this was my comparison of the Duets and the INT-25 using the S1x. I was using the Grimm MU2 with both amps, and with the Duets, I used the Grimm as a preamplifier directly into the Duets.
I replaced the AGD Duets with the Pass INT-25 with very high expectations, and a lot of the magic I was getting with Duets was gone. It still sounded very good, but not emotionally engaging in the way the AGD Duets were, which surprised me. I hadn't run the Pass for 6 months, so I thought it needed some time to warm up, so I left it in for 3 days, and that might have helped, but for most of the music I listen to (a lot of neo-classical piano & strings, alt and indie rock, world music and some jazz) the INT-25 lacked the emotional engagement. Some difference are that the INT-25 is RCA, the Duets are XLR, and the INT-25 is designed with some "pleasing second order distortion", while I think the AGD has lower distortion and also has a higher rated power (300 W at 4 ohms, 150 W at 8 ohms). The Duets were richer, more detailed. more natural sounding, and very dynamic with very well defined, tight and engaging bass. Kronos Quartet's Pieces of Africa, which has a lot of dynamic range, was just stunning with the S1x and Duets, the best I've heard it. |
@kirkwallace Thank you! Thank you for this — really appreciate the care and detail you brought to your impressions. We have quite a bit in common: I've heard all those amps as well, and I've also visited the YG showroom, so your reference points resonate with me. I think you've actually put your finger on exactly why it's so difficult to draw firm conclusions from comparisons like ours: room acoustics, amp-speaker synergy, and perhaps most importantly, what specific sonic characteristics produce an emotional response in a given listener — all of these vary enormously. Your Songer S1x pairing is quite different from my system, and what makes the AGD "click" emotionally in your room with your speakers may involve entirely different mechanisms than what I'm hearing in mine. Two listeners could hear the same two amps in different systems and come away with opposite rank-orderings, and neither would be wrong. So rather than seeing our impressions as contradictory, I'd treat them as independently confirming that these are both serious contenders worth attention — and that the AGD in particular seems to hold up across a surprisingly wide range of contexts. The YG visit is a good example of that. Thanks again for sharing this so thoughtfully. |
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