Speaker buzz and speaker a/b question

There's a lot of posts about speaker buzz but I can't seem to find the direction I'm looking for.

Right speaker is buzzing at certain frequencies. Took the speaker wire from right and hooked it up to left speaker and the left speaker started buzzing and right was fine. So I replaced the speaker cable. Still hapening. So I've isolated the problem to my NAD C355 (I think). Suggestions?

My first inclination is to hook up the speakers to the Speaker B inputs on the amp to see if it takes care of the buzz. Any quality or imedance issue with running the speakers only off Speaker B and leaving Speaker A blank?
Unless your manual indicates otherwise, there should be no problem with running your speakers off of "speaker B" inputs. That would eliminate one other source of trouble (the "speaker A" connection).
Thanks. That didn't help though. I think I narrowed my problem down to my Airport Express. Swapped it out. Buzz is still there once in a while, but overall seems 1000 time better