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

@whitestix 

my take is that the best Class D GaN chipped-amps, such at Atmasphere sells, is the new norm and standard of excellent for stereo amplification.  I have heard the Atmasphere amps at Axpona and they were sensational.  

Thanks for commenting. This has been my hope as well, and this thread has my experiences in trying out various Class D amps to see how they compare to one another, to my tube amps, and to two Class A amps. I'm keen to try out the Atmasphere to see if they beat or equal tubes and Class A, for my ears and taste.

I'm curious about your take on the amps – which Class D GaN chipped amps have you heard, what did you compare them to, and did you manage to keep variables (room, system, listening position) constant when you did? In other words, how did you arrive at your take on these amps as the new norm and standard? Thanks again for posting!

This is a curveball but who have tried tube DSP from something like a streamer/preamp combined with a class D amp, and how does it compare to the real deal taking into account tube rolling and various tube sounds?

Not sure about that last question, but I have been reading about ROGUE and am curious if anyone has tried the Dragon? Apparently they have won some nice awards, commentary.

The Rogue approach includes a tube in the circuit – apparently, their designer found this was a way to avoid some of the negatives of designs without a tube.

These are negatives that – many here are saying – have been solved with the recent designs we've been discussing, but FWIW, here's another engineer's

 approach to this Class D design topic.

From Rogue: "Our proprietary tubeD circuit topology actually integrates the tube section into the amplifier yielding the smooth natural sound that only a tube amp can provide. With uncanny accuracy the Dragon Monoblocks deliver stunning dynamics and transparency without any of the edgy, etched, or grainy sound that often accompanies solid state designs.”

Another  Interesting interview, here, with Mark O'Brien: https://www.psaudio.com/blogs/copper/a-conversation-with-mark-o-brien-of-rogue-audio

O'Brien claims Rogue was the first high-end audio company to release a tube/Class D hybrid, back in 2011, when Class D "finally started sounding pretty good." The underlying logic is that a hybrid design offers the smoothness of tubes combined with the bass speed and accuracy of the best solid state.

He describes Rogue's proprietary "TubeD" circuit topology as one that integrates the tube section into the amplifier's output stage — not simply a tube circuit placed in front of a Class D output section (as with, say a tube preamp approach). "TubeD" employs a small amount of feedback from the tubes to create tube-like behavior in the Class D output modules, making the solid-state devices sound and test like large high-performance tube amps.

In another post I found, he described why he uses 12AU7 tubes. Apparently, it's because: he believes it sounds good and does an excellent job rejecting power supply noise while offering a low output impedance to the amplifier for proper signal transfer.

O'Brien's view about what makes or breaks Class D's reputation for "edginess":

"Another important aspect of this design is its use of large linear supplies for both the power amp and preamp sections. I'm a firm believer that the switching supplies used by many manufacturers are responsible for the 'edginess' detectable in some amp designs."

Source: https://everythingaudionetwork.blogspot.com/2014/03/audiophile-review-rogue-audio-pharaoh.html?m=1

"@audiobeatnik ...not tube-like but not the earlier Class D “thinness” that I have heard. It has more meat on the bone than my previous Class D experiences. Now we are getting somewhere!" 

PS Audio M1200 Mono amps (tube/ClassD):

A clip from an older article with comments regarding a front-end tube design as part of their Class D mono amps. These have been around for a while now too. How do they compare with others discussed here so far, who can chime in to add more?

https://theaudiobeatnik.com/review-ps-audio-m1200-monoblock-amplifier/?utm_source=chatgpt.com

@hilde45  I’ve been on a bit of a journey lately. A couple of years ago I bought a pair of Magnapan LRS+ and fell in love with their presentation. At the time I was using an AGD Tempo amp, and at anything above a pretty low level it strained to keep up. But I am aging with a bad back, so no class A behemoth for me. So I bought a Bryston 3B3 (AB), which had plenty of power but was a bit clinical. Then I bought a pair of Rogue Dragon Monoblocks. Closer! But fine tuning was crucial.

First, context: Aurender N200 > Denafrips T+ 15th > Backert Rhythm > Dragons > LRS+ (full range), KEF KC92 sub. 

First I replaced the Zavfino speaker cables with Silversmith Fidelium. Oooh! Then I replaced the PSVane Horizon 12AU7’s in my preamp with a pair of Ray’s Select 12AU7. Better yet! Then I replaced the JJ 12AU7’s in the Dragons with NOS Mazda 12AU7. Holly SH*T!!! 

Full bodied, gorgeous textures, air, incredible image depth and spacial separation. And not a hint of that upper midrange bump that I find so annoying. I’m a happy camper! Except maybe I need to get a pair of the X series Magnapans? (eye roll here).

The only other system that even came close in recent years was a Rogue RP-7 pre > Pass XA-25 > Spacial Audio X-5’s. But while engaging, it was a different kind of presentation and lacked the transparency of my current system. 

Your situation is obviously different with very efficient speakers.