I finally got to crank my new amp yesterday at my buddy's house (i live in an apartment). The speakers were giving off a terrible bass feedback kind of sound...louder than the amp itself. Usually happened when I was palm-muting. It is extremely obnoxious sounding and pretty much ruins an otherwise killer crunch sound. Any ideas what the problem is? The speakers are 2 Carvin 100 watts, 8 ohms each. If they're wired parallel, then the amp should be set for 4 ohms, correct?