The problem occured after installing the new receiver, but it only could have done something to the speaker itself. I flipped the speaker connections so all the front outputs drove both speakers, and I also moved the speakers around the room. I think this might be a very odd coincidence, or because the imaging on these speakers is so good, I only noticed it after getting a good receiver. It's at the shop being looked at right now. For those of you who are familiar with the Yamaha auto setup, the "whip cracking" sound brings out the difference in sound more than anything else. Thanks for all your input.