Sorry for the delay and the short response from before. It was time for lunch
(in Spain we eat much later than the rest of Europeans). I have already taken the coffee, I will try to expand a little more.
As for the
op-amp. In another thread, in the
NC500 thread already commented. Initially the buffer designed was for the
Sonic Imagery. Later it was intended to work for other op-amps, too, but some measured quite badly at first, in the case of Burson and Muse. That is why the logical thing, with the NC500, was to use the Sonic Imagery, my choice.
https://www.audiosciencereview.com/...ements-of-nord-one-nc500-amp.7704/post-193449
If a buffer is designed specifically for an op-amp that already measures well it is assumed that it will also measure well, provided that
good measurement tools have been used during the process.
Yesterday
Bruno Putzeys participated for the first time in these forums, in the thread of the
Purifi 1ET400. We could take to ask what was the change of the op-amp with respect to the
NC400 and NC1200, the
LM4562, if I am not mistaken.
https://www.audiosciencereview.com/...-of-purifi-1et400a-amplifier.7984/post-194984
And you could ask him about 1612 vs 1620.