Thanks. Since I last posted, I've read up and think a dual trace scope isn't an unreasonable instrument to own and is perhaps the only way to get this amp perfectly aligned. I think Fisher had a precision amp in mind when it was designed, and although other users have been able to "rough them in" at first, they found that using a scope turned out to be the best way to get this amp to realize it's potential. I rather like the idea that Fisher put so many adjustments in there in the first place.
Fisher SA300 biasing
Does anybody have any experience setting all of the power tube biases on this amp? The service sheet I was able to download doesn't have any bias currents or voltages listed, only a table of resistances for each valve's pins. There are 7 trim pots in there, one for each channel: hum balance, ac balance and dc balance, the seventh pot is for the power supply's -25v voltage, that's the only one that I understand. I was hoping for an easier way to do this other than calculations after reading from a resistor.