For a weeks my office system, I spend 90% of my listening time with this rig, has sounded odd. Not really bad, however, from bass to treble and especially in the mid-bass to low-mid range things sounded odd and the entire bass region seemed a bit weak. I suspected faltering output tubes (2 6550s per side)
A bit ago while dusting my Cary SLI-80 I noticed that the left channel output was set to 4 ohms and the right to 8 ohms. DAMMIT! With the flick of a switch everything was back to normal.