wrote:

Eeyore wrote:
Keith G wrote:

After an hour I can say it's fine/OK and
if it was all I had I wouldn't be too unhappy, but usually when I swap back
to the valves (haven't got time atm) I find the *improvement* is
instantaneous and reaffirming.

It's called listening fatigue. The break that you give yourself so doing allows
the ear to recover. Now try it the other way round !

Hmmm I read somewhere that the opposite is usually in play. There seems
to be a common bias to prefer the second smaple in an A/B comparison.

Which is what I said.

Graham