Who tried Class D only to return to S/S or Tube

I have gone back and forth about once a week for the past year. The only Class D I have owned is my current NC1200 Acoustic Imagery Atsahs. I also own a McCormack DNA-2 LAE that received Steve's Signature Edition upgrades (the best) in 2014. Before that, solid state with Clayton Class A M300s and M200s, Lamm Hybrid M1.1s, and top SS amps from Cary, Herron, BAT, and McCormack (DNA-500).

It has been difficult to decide whether I like the McCormack or the Atsahs better and I am set up so I can easily switch between them, which has been interesting. From a purely sonic standpoint, the Clayton M300s were the best I have owned but the Atsahs and McCormack are close, and have ergonomic advantages over the Claytons. The McCormack and the Atsahs have slightly different sonic presentations but the differences are not large and both sound great. I would say the McCormack sounds a bit cleaner and more extended while the Atsahs have a touch more tonal density. Both have great bass and, again, the differences are small.

Jeffb28451, while the Class D amplifiers may have been "broken-in," it is possible that a two-day warm-up was not long enough for them to reach their full potential. I would have previously called BS on this notion but, after living with NC1200 monos for the past year, and switching between those and my Class AB amplifier, I found that both need to remain powered up all the time or the amp that is warmed up sounds better every time. Particularly with the Class D amplifiers, it seems they need to be powered-on up to a week for the treble to sound its best.

I also admit that the treble is one area where my Class AB amp beats the Class D amps. Both seem fully extended but the Class D amps seem comparatively a little "shelved-down" in the very upper frequencies, which seems to affect ambient cues more than how instruments/vocals sound directly. I get just a little better sense of venue and infill of the background sounds between players with the Class AB amp. However, there are other areas where I like the Class D amplifiers better, which is why choosing between the two has been difficult for me.

Jeffb28451, while the Class D amplifiers may have been "broken-in," it is possible that a two-day warm-up was not long enough for them to reach their full potential. I would have previously called BS on this notion but, after living with NC1200 monos for the past year, and switching between those and my Class AB amplifier, I found that both need to remain powered up all the time or the amp that is warmed up sounds better every time. Particularly with the Class D amplifiers, it seems they need to be powered-on up to a week for the treble to sound its best.

I also admit that the treble is one area where my Class AB amp seems to beat the Class D amps. The Class D amps sound comparatively a little "shelved-down" in the very upper frequencies, which seems to affect ambient cues more than how instruments/vocals sound directly. I get just a little better sense of venue and infill of the background sounds between players with the Class AB amp. However, there are other areas where I like the Class D amplifiers better, which is why choosing between the two has been difficult for me. Maybe I should just keep both.

One cannot simply swap out an AB amp for a D. The system must be coherent and matched.

This seems to be in response to my post so I will bite...and ask what do you mean by "coherent and matched?"

I didn't mention that I tried the amps with three different preamp options, two of which were made specifically for the amplifiers, by the same manufacturer that made the amplifiers. Because two of the preamps have low impedance outputs, those two matched well with either amplifier wrt impedance. The highest gain preamp was +6dB and the other two have zero gain, while the source is 4V. These numbers work well with either of the two amplifiers. Are there other parameters that need matched? Regarding coherence, what attribute or parameter would make one preamp more "coherent" than another when used with a Class AB or Class D amp, and couldn't the same preamp be "matched and coherent" with both of those amplifiers?

After a year and a half, I have finally divested myself from a pair of very good sounding Ncore NC1200 Acoustic Imagery Atsahs, but I have not settled in on their final replacement.

The original comparison was between the Class D Atsahs and a Class AB McCormack DNA-2 LAE that I own, which SMc Audio upgraded to their Signature Edition in 2014. The SMc-McCormack is an excellent sounding amp and, in comparison to the Atsahs, simply sounded more "real," primarily due to a better portrayal of spacial cues between musicians, a better sense of venue and perhaps a better ability to portray micro-dynamics. In addition to the upgraded DNA-2 LAE, I also have here a pair of Class A Lamm M1.2 Reference monos and, as of Monday, I will have a pair of Class A Clayton M300 monos. I plan to keep either the Class A Lamms or Claytons, and then decide whether I want to keep the Class AB SMc-McCormack too.

Reviews have been very positive about the Class D NC1200 amps, and I found them to sound quite nice, with standout features being a dense tonality and excellent (although possibly overdamped with some speakers) bass, as well as several very attractive ergonomic characteristics such as small size, low heat, low energy usage, and zero self-noise. Unfortunately, in comparison to the mentioned Class AB and Class A amplifiers, I felt the Class D Atsahs were lacking that last bit of lifelike ambience, as if music is not being played live or by a band in a studio, but rather as individuals cutting their own tracks and then merging the tracks to make the whole.

In my opinion, the reviewer over at Mono and Stereo actually got it mostly right (although too critical), with his review of the Mola Mola Kaluga, where he states,

"The familiar music didn`t sound much familiar through the MOLA MOLAs; in the midrange the voices did not posses enough dose of “human touch” to sound real.
All notes were there but the illusion of musicians standing in front of me wasn’t convincing at all. The music didn’t sound inviting and involving, it was just… there.
The emotional content was missing and the tonal colours were somewhat bleached.
For lovers of analog reproduction and concert goers the sound could also be quite fatiguing and plain boring."

And he concludes with .......

"As for the KALUGA monos…in my view the time has not yet come. Perhaps many people will find them good in what they do and will happily live with them for many years, but it should be pointed out that class-D amps offer a very different sonic perspective from what one hears live OR with good analog amplification, be it tube or solid state - regardless of the amp`s working class. If the sound of KALUGAs would be declared as very lifelike, then I fear we would be sending a wrong message to the audio amplifier industry, not to mention deny the reality. There is just no way one could consider both, the analog and switching amps equally capable of materialising that grand illusion of performers playing and singing in front of us - this is just impossible due to huge differences in sound."

One designer of Class AB amplification once told me, in his opinion, the Class D amps he had heard at that time had been "dynamically challenged." I believe he was talking about that micro-dynamic 0 to 60 thing. Some might call it sounding "overly smooth."

Based on my time with the Class D Atsahs and assuming (from the many positive reviews) that NC1200 is at or near the top of the Class D amplification chain, then the current state of Class D amplification has resulted in amplifiers that can sound very good, and that offer excellent ergonomic attributes, but still do not compete in every way with upper level Class AB or Class A amplifiers with regards to creating a musical whole, or a realistic illusion of performers and venue.

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