jkohn & Chris,
I had (what I think is) the exact same symptom in my VP 100 that you describe for your 150's. It wasn't noticeable during the movies or music I had played up to that point, but was very evident during the subwoofer crossover check calibration on the S&V disc. I thought I'd broken something within my first week, but while talking with Joe V, I was able to localize the "giant mosquito buzz" to one of the woofers. He had me check for dust on the cone, and while gently pushing on the rubber "boot" surrounding the woofer, the sound miraculously went away. I was thinking it could be a short of some kind since I was able to recreate the buzz by pushing again on the boot. I pushed on the boot one final time to make the buzz go away, and all has been good for over a month now. Joe shipped me a new woofer, but I haven't installed it yet because the "buzz" hasn't returned. Somewhere online (this forum or HTF), a poster mentioned tightening the hex screws around the woofer/tweeter on his Axiom speakers as they were a bit loose. I checked mine and the screws on my center were a bit loose. I tightened them up "just to be sure", and haven't had any problems.
I'm no speaker expert, but your symptoms sounded exactly like what I experienced. I don't know if I have (or had) a short or a loose connection, but things worked out great in my case, and I continue to be blown away by the performance of my system. Good luck, and give Joe a shout if you still have problems.
lando
