making this god-awful hum/buzz/zz-wistle sound in mid-freq output. I'm not a "speaker head", but to me it sounds like the cone is torn. It's just over a month old, and I have an apt to bring it into the dealer on the 1st to get it checked out, but the more I know before I go in, the better...not that I'm expecting to be handed a line, they're very professional, but I'd like to be able to describe the problem better than I am currently able. Any advice?