Dana:
While 'm glad that everything is working right, I'm surprised that the m80s would have enough output to cancel out your sub. In fact, moving the M80s closer to the wall would reinforce their bass, and theoretically cancel out
more from the sub.
Did you ever play with the phase control on the 350 (because this is the type of situation that warrants that control)? It changes the "phase" of the sub output so it matches the other speakers. You don't, in effect, want one woofer "pushing out" while one next to it is "pulling in" because the sound wave created by either is inverse to the other and will cause cancellation. This is also why you want to make sure your speakers are wired correctly in terms of your "pluses and minuses".
Since I had so much fun creating the wiring diagram last week, this week I've made a "Phase Diagram":
(This may have been more than you needed to know, or too basic for you, but now I can copy and paste the text and graphic the next time someone has a question on the topic!
