I have a GKRBIII400 head puts out 240w @ 4 ohms. when I run this with my Ampeg HVT 4x10 cab it seems I can always get a muddy, farty sound at high volumes. I have adjusted every knob into every possible configuration and it still does this. The cab is rated for 500w @ 4 ohms, if I upgraded my head would this solve my problem? For example if I went to a GKRB1000, or a Carvin1000 would it clean it up? Or, could I bridge the RB400 to double the output by putting a splitter cable which has two jacks for the two outputs from the head into a single input into the cab without damaging the head?