Class D amps seem poised to take over. Then what?

@ricevs 

Are you 100% percent sure the Rouge ICE amplifiers will sound the same, as good, as the Legacy amplifiers that Doug reviewed? Have you seen inside the Legacy amps? Is it possible they have performed some upgrades or other power supply changes etc? 
Looking at the Rouge amplifier now.  Thanks! 

What's after Class D?

Well, as usual, probably improvements on what we've got. Sounds like GaN (Gallium Nitride) transistors can handle very high voltages and very high current and very high frequencies. Perhaps useful for class A, A/B, G etc - because they cmight vastly reduce output delta t, so feedback works better -  but almost certainly wonderful for D. Much better edges, so fewer errors for the system to compensate for.

And, of course, all this hifi stuff is for pleasure. It's nice to know that product X has immeasurable distortion under all circumstances, but of you prefer listening to product Y, then go for it. I prefer Burgundy, but there are those who drink Bordeaux. Neither I nor they word - or rather should - argue that my preference is 'the absolute best'; just that 'I prefer'.

It's true that many designers want accuracy first. Good! But if you prefer the sound of something else, go for it.

But don't tell me that you're right and I'm wrong for enjoying my Kii Threes. 

Oh, and I had my first class D amp way back when. 1965 or so.

The Sinclair X20. 

http://www.vk6fh.com/vk6fh/sinclairX20.htm

Built it myself, I did. If you soldered a short wire to the collector of the driver transistor, you could pick up a distorted version of what I was playing (from a self-electronic'd reel to reel) at intervals all the way up to about 30MHz on the AM band for quite worrying distances. So I put it in a metal box.

It had a class A front end, so it must have been good...

I’ve tried a couple class D units. They were good but not great to me. I’m game to try some more. 
Anyone try a class G amp?  I had a Creek class G. Very cool topology: first 25 watts was all Class A and the switching side kicked in north of that to output 170 watts into 4 ohms. Sounded lovely with PSB Imagine T2s. But I went horns and tubes.