Ok, so got a new GK backline 600 (300 watts @ 4 ohms) hooked up to a new Fender Bassman 15" cabinet which is 8ohms and 250 watt, 500 watt peak. I figured that even at 8 ohms the 150 watts from the GK head would be enough to power the cabinet but I think I was wrong. I get horrible farting, fluffing, sounding distortion even at low volume. My bass is an Ibanez soundgear with active electronics and I changed the battery thinking that was it, but it sounds find on my smaller 100watt ampeg combo. Is this a case of underpowering the cabinet? Do I have a defective amp or cabinet?