Class "D" amp? I do not have a clue. Do you?

That goes both ways when it comes to power. A large improvement was made not only to my Nuforce amps but all else in my system when i invested in power regeneration for my systems power supplys.

Also trying out the latest from Nuforce there Ref 18 and i can say without hesitation King Crimson will not run you out of the room if fact you will want to get comfortable and hear the whole lp. IMO

It is also possible that new generation is just only a little bit better (like BC Ref1000M with extra power supply caps) and "new generation" allows some critics to reevalute (read: save face) since others scored them much higher. For instance REF1000 was evaluated bu Martin Colloms for 10.5 points while Krell got 130 - that's less than 1 of 10. Ref 1000M is Stereophile class A. Sound like two completely different amps but in reality both use exactly same Icepower module with built-in SMPS.

The first class D amp I was aware of was made by Infinity way back when (before they made speakers). The idea is nothing new and has been around for awhile. I think most car amps are Class D. It makes allot of since in auto and mobil applications. However, a liner power supply is still the way to go for the best sound and all designers know this. It does cost allot more and wastes energy and maybe it is getting harder to source really great transformers?

6550 - The problem here is that SMPS is small. It is hard to believe that something smaller can be better. It is line and load regulated and basically the same thing as class D amps that win Stereophile class A classification.

It is difficult to change traditional way of thinking (you being example of it) but some great companies (like Linn) used SMPS for class AB amplifiers for a long time. New $48k Rowland class AB amp uses SMPS. As for being better suitable for the car since it is always used there - you can make the same argument for transistors (tubes for home, transistors for cars). I'm pretty sure it was the case at the beginning of transistor amps in audio.

Why not to listen first and learn what is inside later?

Class D refers to the output device, not the power supply. Class D amps can have traditional power supplies or switch-mode power supplies.