I’ve identified the problem. It’s a tube in the preamp that was going bad.
it was intermittently causing distortion and reeking havoc with the sound, from one day to another. After replacing the tube, the set sounds better than ever (or so it seems after the nightmare.)
it was intermittently causing distortion and reeking havoc with the sound, from one day to another. After replacing the tube, the set sounds better than ever (or so it seems after the nightmare.)