Tim,
I think the main thing is to shop techs. The OP was not served by the original guy who saw $$. In all my years of fixing stuff and as a process technician in a place making integrated circuits and discreet, the #1 thing I learned was to get a good description of the problem and what happened.
Asking the right questions are critical.
People don't realize they are setting themselves up with stuff like 'It's broken'. The more info a tech has, usually the better.
Is the NAD still available for inspection? I'd sure like to see it and try some contact cleaner. Worst case is you're no worse off than you are right now......
When I brought my old Carver Cube (M400t) to the tech, I was able to give a pretty good description of what / when / where and the POWER GLITCH that took it out. The electric company bought that fix for me, since I kept good records and knew exactly when my amp went south. What a Chinese puzzle box it is. It worked another 5 or 6 years after the fix, so I guess I got my $$$'s worth.
I've never worked hi-fi but this amp doesn't sound too broken for a little experiment. You may get lucky and fix it. Contact cleaner, anyone?
My preamp for the Cube was a Kenwood integrated amp that I cracked the case on, and found (sheer luck) that the main board and preamp board were strung together with jumpers. snip snip / solder and I had a preamp which lasted until I could afford a real preamp.
Rosy picture? Sure! My pleasure! No harm in trying something rather than getting a 400$+ bill for a repair. Always ask for the parts back, too. Sometimes my rants make me laugh, too.
