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

"Ref1000 can drive 2ohm delivering 40A "
That means that its peak voltage is 40x2 = 80 volts. Its not bery good!
With medium efficiency speakers the MEASURED peak voltage is above 100v. This why Spectron amps have peak voltage of 240 volts (to cover poor efficiency speakers too). As I understand switching power supplies also generate high frequency noise. I believe these are two the main reasons why high caliber class D amplifiers like Spectron and Mark levinson (No 53) use traditional transformers.
The single exception is Jeff Rowland 312 which uses switching power supplies with PFC (power factor correction) and for its $15k price provide very good sound.

DC Offset: any semi-decent amplifier ( e.g. Spectron I own and enjoy!) has protection circuitry. Richard Vandersteen may have some bad experience with either old design or new "cheap" class D amp. Today its not a problem (if done right)

Mike

"Switching power supplies generate high frequency noise that is easy to filter out and non audible. For this reason Rowland uses switching supply in Capri preamp and he is very noise conscious guy (he used batteries in preamps). "

Hello Kijanki. By chance I owned Capri before I got my "heavenly" full tube Joule-Electra LA-300ME preamp. As strange as it may sound, this tube amp is more silent then Capri.

Next, I spoke with Simon from Spectron yesterday regarding asserion that high-frequency noise (or signal) is inaudible.
He says that then you emit hi-freq test signal it is indeed inaudible. However, then this hi-freq signal is a part of the mixture with other signals i.e. real music then due to the non-linearity it effects human perception of the music and effect listener fatigue.

He agreed with you, however, that future audio equipment will have only (perfected) switching power supplies even in class A ss amps - which will not have a weight of huge transformers and somewhat less of the heatsinks; the same with high power tube amplifiers.

fascinating topic !

Mike