A guy on the marshall boards been changing speakers/tubes back and forth, even tried my bias recommendation he thought it sounded warmer some but didnt say aww man muddy or too bright and kept it at 30ma who knows.Get your cables in check at least get a good one and plug straight in and see what it sounds like,tube screamers arnt true bypass unless you get one that is so turning it off will effect tone some. I tried one and it colored my tone too much I dont get the hype! clean boost are better for boosting if you get the right one IMO