Comments please on: NAD M23 vs c298 vs. other newer Class D

Started doing some extended comparisons between:

(a) Hypex based amp (DIY from friend who’s a master builder)
(b) Purifi-Eigentakt 1 amp (NAD M23)

Generally the NAD was better:

• more “rounded” or easier on the ears for louder passages (e.g. vocals, piano, sax) that the Hypex felt “cringey”
• more body, presence, texture in instruments -- more “reality” to them compared to Hypex
• good soundstage, width and depth (but not better in this regard)
• fast and dynamic (but not better in this regard)

That’s the report so far.

Overall: NAD winning by more than a little bit.

My curiousity about @atmasphere Class D amps is growing. Watching reviews and interviews with him about the amps. At the moment, I have a strong suspicion that what I like in tube amps is going to be more present in his Class D’s than in the M23.

For now, though, the trials -- NAD M23 vs. Hypex and then the winner of that competition against the Pass XA-25 will go on.

The key question will be: what do the better Class D amps bring to the table that the Pass cannot with my very efficient speakers?

I am NOT getting rid of the Pass. I am looking to see whether there is something in a Class D that add a new and different character to my stable of amps.

Well, I am very interested in the outcome of this evaluation. Please don't "Ghost" us on the results. I'm not saying you will, just hoping to hear the results from your well executed trials.

I'll report in again.

Honestly, after doing a lot of different trial with gear – comparing tubes, different amps, speakers, DACs, preamps, etc. I find this to be genuinely exciting.

There are a lot of Class D makers flooding into the scene – search for "class D" and companies like VTV or Hattor or many others – there's a lot of activity that not just coming from China. (No slight there, just that there's so much coming from China.)

I really do have a strong suspicion that they KEY to Class D for audiophiles is going to be the intelligent and music-sensitive voicing part of the design process. Paul McGowan talks all the time about the back-and-forth between listening and designing that goes on at PS Audio, and I've also got the strong impression that @atmasphere is a real listening-designer. I've never heard a PS Audio amp that's has suited my tastes, but maybe I need to try them again.

Anyway, I'm looking for the "musical class D amp" and maybe that's a unicorn but I'll let folks know what I find and be interested in comments and their own adventures.

"@hilde45 music-sensitive voicing part of the design process.". ..

Yes. All technology jargon and specs and measurements aside, I've followed and bought amplifiers after I learned about designers with what I think of to myself as "musical ears" with an attention to detail about how the sound presents itself.

We get it that you are an engineer. Here is the curve ball question about the "sound". When you compare your own Atma-Sphere TUBE amplifiers to your new Class-D mono amplifiers, what can you share about the sound - What is similar and what is different about the sound stage, depth, placement of the singers voice (more forward or back), and what about channel separation and instrument separation. 

@decooney On the systems I play a lot (home and at the shop) our OTLs and our class D amps sound very similar. There are two main differences. The first is that the class D amps are slightly more focused, so its easier to tell what's going on in the rear of the sound stage, there's slightly more detail. 

The other difference is how bass is played. On the shop speakers I don't notice this as much as at home. My home speakers are 16 Ohms and 98dB and use horns. They are designed to work with amps with a high output impedance. The class D amps have a very low output impedance and so don't make as much energy in the bass regions of the speaker where there are impedance peaks. To sort that out I had to change the settings for the midrange and tweeter, which are controls on the back of the speaker. Most speakers don't have these controls because they are intended for amps with a low output impedance. 

Once I got that right I didn't miss the tube amps at all. 

So in a nutshell they sound very similar as they share the same smooth character in the mids and highs.