I haven't dealt with manufacturers per se but, after about eight years of flawless service the sound of my Primaluna Integrated began to degrade. I phoned Upscale Audio and guickly got a tech on the phone who described the flavor of every replacement tube they offered. I made my decision, and it wasn't long before the tubes were at my door. And yeah, the tubes made me happy. Maybe six months later, both the Primaluna's selector and volume knobs developed noise & glitches (I'm certain a good part of this is due to my relocation from sunny SoCal to a veritable tropical rainforest). Via email, Upscale encouraged me to unscrew the bottom of the amp, spray the offending moving parts with Deoxit and then spin the knobs around a bit. To be sure, I was a bit nervous doing the surgery but, again, everything worked out perfectly. It was also a treat to see how beautifully the amp was assembled. The amp has never sounded better.
