What are the best GaN Amplifiers available today?

I can’t think of a reason why they wouldn’t work just fine. For starters class D amps tend to be low noise. I run mine on speakers that are 98dB and they work fine at low levels.

My findings concur with that. All my Class D amps are dead quiet, perhaps all teh quietest I have ever owned in 50 years, from my largest and most costly in teh Cambridge Evo 150 (Hypex Ncore) to the smallest in my little $80 Fosi integrated (TI chip) and everything in between including a somewhat older Bel Canto c5i and the 4 in my Vanatoo Transparent One active speakers. Even the oldest and most costly BEl Canto ref1000m 500w/ch monoblocks the Evo replaced were always dead quiet and all excellent at low volumes, though perhaps just a tad rolled off in the high end. These are all with typical average not high efficiency speakers which typically are more sensitive to any noise in the signal.

I would think low-volume performance in Class D amps is not solely reliant on low noise (albeit that being a huge factor), but also the amount of attention in delivering the appropriate quality and control in those first few watts?

I would think low-volume performance in Class D amps is not solely reliant on low noise (albeit that being a huge factor), but also the amount of attention in delivering the appropriate quality and control in those first few watts?

The first few watts are always the best...then its always down hill from there as the volume goes up.

Playing at low volume does not require a lot of watts so most any good quality amp should do well.

As I think mentioned earlier, human hearing and Fletcher-Munson is teh key issue for good sound at low volumes in most cases. FInding an amp at most any realistic cost that can deliver enough power for low volume is just not practically a problem.

Now in teh case of high efficiency speakers, where the effects of just a few watts gets magnified, it is more of an issue perhaps but so also is noise.

Easy cases like low volume is where measurements are your friend in particular. That is the only way to truly know what performs best OBJECTIVELY or better than others. Subjectively, anything is possible. A poor quality overly bright amp may sound better at low volume due to aforementioned Fletcher-Munson, but crank up teh volume and be prepared for greater chance of ear bleed.

Fletcher Munson Curves

Ralph is in in the room. Cool. Met him at Axpona. Great guy with great stories. Thanks to jeffseight for introducing me to Ralph.

As an update. I'm still running Orchard Audio on my Center and Surrounds. I got a killer deal on a pair of Black Ice F100's that I couldn't pass up. 

https://photos.app.goo.gl/9Te5RTN1NUyC9G3NA

I've also listened to a pair of Atmas-Phere Amps that Ralph designed on a pair of PS Audio FR30's. They are a good match. 

If we're talking THE BEST, regardless of price...Aavik and T+A.