HiFiAl
Then if the "noise" was not present during the silence parts then it can not be the equipment. If the noise was inherent in the equipment you would hear it all of the time, even during the moments of silence.That's not necessarily the case in all designs. Let us assume for a moment that the signal has to pass through some filter before leaving the amp. This filter will only work on the signal, therefore it will do nothing when there is no signal passing through the amp. Therefore, this is a scenario where the noise will be added only to the music (signal), not the silences.
Many OEM class D designs have had noise issues in the past and the latest generation seems to have corrected that. The NC1200 is in in first iteration, so I'm confident that this is an issue that will be dealt with in future generations.
This is a quote from Positive Feedback reporting on the NYAS 2013:
Sanders Sound & Merrill AudioAs you see, I'm not the only one to have perceived this odd behavior in the context of the Merrill Audio Veritas amps.
Right across the hallway was another electrostatic speaker, the Sanders Model 10c, and another variation in sound quality. Power was provided by the Merrill VERITAS Mono Blocks, which use the latest Hypex Ncore NC1200.
Radically different than the Martin Logans, the expected transparency usually associated with 'stats wasn't in evidence. The midrange on down was heavy and the top lacked a bit of sparkle.