I dont think there are many QC issues with the NAD amps, there have been issues with cd players in the past but those have since been resolved. And this is coming from someone who has had mine in for service but i would buy it again.
The cheap jumpers are no worse than any other things you would find on another brand. theyre just your basic U shaped metal jumpers. I dont believe that changing the jumpers will dramatically make the sound better, maybe a little if your lucky.
I would say that the main "flaws" in the amp are within the pre-amp section. I have recently stopped using the nad's preamp section and replaced it with a diy tube preamp,.. which cost me about $250 total. The sound has improved quite a bit and the upgrade was definetly worth it.
I have now heard that tube magic people always rave about and i too am hooked.
Bottom line is the NAD C370 is a great amp, its got more than enough power and sounds very good with the M80's.
