Thanks for the reply Robin. Much appreciated.

I’ve tried the checks you suggested, to the limits of Google and my abilities anyway. Unfortunately, what I’m seeing doesn’t make a lot of sense to me:

– The negative feedback loop wiring is showing zero resistance from the 68K resistor to the speaker input jacks … that’s good.

– Neither of my speakers show zero resistance from the positive to negative tabs whether plugged (5.6 – 6.6 ohms) or unplugged (0.7 – 2.7 ohms) … that’s good … I think.

– The negative feedback loop resistor is colour-coded 68k (and tested at 68K before I installed it … I checked them all), but it now reads 1.5K with a probe on either side … that seems not so good (I would have expected it to still read 68K … unless it’s receiving a signal through both the resistor and the circuit?).

– Resistance readings on the impedance switch tabs fluctuate, then return to what they were when I flip that switch … that seems not so good (I would have expected the “off side” impedance switch tabs to go to high resistance when the other side was selected, no?).

I’d appreciate any insights, even if that’s to cut my losses and protect the amp by finding a tech to check it out …