Atma-Sphere Class D… Amazing

I have Atma-Sphere Class D and suspect it outperforms every other brand in its price category.

I can’t recall if Ralph mentioned anything about break in time, but he did say they have virtually no warm-up time to achieve best performance. I never noticed anything to contradict Ralph’s statement. Idle current is so low that it invites leaving them on 24/7 yet if the amps happen to be cold, they need little to no warm-up to sing.

A friend of mine is interested in an A-S class D integrated. He mentioned having read that Ralph’s Class D "sound like a tube amp" in only the best way. I have heard various models of Ralph’s OTL and a lot of great brands of tube amps.

I agree with Ralph and others who say his Class D sounds like the M-60 OTL above the bass range, which by any metric is a long-time tube amp gem (having won more awards than maybe any other current production amp.) It seems important to add this caveat: the ideal OTL load is between about 12 and 16-ohm with benign phase angle, which is rare, plus higher than average sensitivity. Class D has no such current limitations and can drive loads below 4-ohm which is verboten for OTL and a ratio of transformer-coupled tube amps.

OTL have a unique signature in the bass range, not necessarily worse or better than SS, just different, hence the qualification "above the bass." In the range of bass instrument fundamental tones, Ralph’s Class D sounds like a good typical class D amp: quick, neutral, superb and powerful. Of course, bass harmonics extend well into the midrange and treble where the Class D is very transparent in this category.

AFAIK for all Ralph’s prior amps, Ralph included a U-shaped copper shorting pin. Using the RCA input required users to short XLR pins 1 and 3 (1 is neutral/shield, 2 is positive signal, 3 is inverted signal; 3 shorts to ground to shunt the entire inverted section of the balanced input to minimize potential noise.) The RCA input of current production A-S Class D requires NO XLR shorting pin, hence none is included. Ralph said shorting XLR pins 1 and 3 has no effect on noise while using the RCA input.

A-S Class D vs. a highly regarded $3k SRP stereo amp with possibly the all-time lowest SINAD specs, only about 13#, not class D, a patented circuit, released around 2015 and winner of a ton of awards.  The stereo amp had audibly more musical detail.  For unknown reason and there's no way to prove this true or false, I got the sense the stereo amp was more "accurate" or linear; yet in no way did this last point make me favor it.

IMO the A-S Class D had blacker background, the stage was audibly bigger in all 3 dimensions and had an upbeat, more musically satisfying presentation.  Images had more body/density and more air around them.  In the AB test the stereo amp simply sounded more sterile and mechanical.  Like a sharply dressed, quick talking boy that arrived to date your daughter, but he just seems a little disingenuous; he makes you question his motives.  Why does he have such a perfect exterior?  Is it an act?  I want to get to know him better, but he never lets his guard down.    

Overall I favored the Class D significantly more than the stereo amp.  Yes, the Class D costs more but I suspect most people that can afford the stereo amp can stretch funds and/or save a little longer for the Class D, which seems like even better value than the stereo amp considering the awards heaped on the latter.  

OP typed:

in my system I found the Atma-Sphere Class D was slightly better than the Pass XA30.8. 

Holy smoke people!  Let that sink in. That Pass amp is a current, state-of-the art true class A power amp designed by one of a handful of the most revered and respected SS power amp designers who ever lived.  SRP is similar but cost of ownership is not: while idling the XA space heater burns wall current at the rate of about 270W; think of 2.7 100W incandescent light bulbs.  I presume Ralph's Cass D burns about 10W if that much.     

@fsonicsmith

I...commented that the parts could not justify the price.

What exactly and specifically is the parts cost? Did the deleted post contain an exact and specific accounting of the parts cost? What date was that accounting performed? Is the poster familiar with parts cost inflation in the past year?

If the post lacks the # requested above, I submit to readers a potential the poster conveniently ignored for the deletion: there was no factual basis for the opinion expressed as a fact.

Even if the # was posted: what is the exact and specific threshold for ratio of parts cost to SRP beyond which a product is deemed "failure?" Readers need to know this ratio to confirm the poster is being consistent and not being derogatory for some hidden agenda.

Also, does every single audio item the poster own meet his own criteria?

The omission of all this data surely justifies the deletion, a personal attack on the product masquerading as an innocent opinion.

Lastly, to imply that any product’s SRP is justified solely by passing the value test described herein is simply wrong. To be polite I won’t say such test is naive, but I can imagine some thinking that.

@ johnh

Thank you for your fantastic post.  Surely this type of post with so much personal experience with a good number of the most relevant currently produced amps is literally the definition of advice that "money can't buy."  No pro review I've ever read (that I can think of) has so much valuable info for direct comparison.

Amir @ Audio Science Review has good test gear and has tested the Purifi.  Purifi tests at the very highest level as does an amp I referred to and owned.  Oh, if we could only read test results and make purchases based solely on these tests!  But we can't because I owned one of those amps and Ralph's class D is at least 1.5 to 2 clear steps up the food chain in audio performance.  (Maybe Ralph's class D would test similarly but I won't be surprised if it does not.)

I recently had here a superb $40k DAC and pair of class A $60k/pr mono blocks.  I know the designer, who told me personally that he could improve the DAC's static test specs but would not because it would degrade its audio and musical performance.