However, I realised that I had, metaphorically, been barking up the wrong tree. the beautiful performance of the amplifier derives not only from the quality of the parts, but from the SYNERGY they bring about assmbled with enough care and diligence. So, I hypothesized, to get the maximum benefit, the entire amp must be thus treated as one, and so I ordered 300 l of liquid helium (eye-wateringly expensive ,but still the closest I could realistically afford to get to 0 K) and after cooling an expanded polystyrene tank, in went the helium and shortly after the amplifier. Judging by the amount of helium boil, the amp's electrons must have been very incoherent indeed but a few hours later it was all done bar a slow thaw. The next day, to test it, I plugged everything in BAR an audio source so I could experience pure amp noise floor. After turning it on, absolute silence, even when the attenuator was at 0 dB. Amazing