I've been reading the previous posts concerning the mo' bass head; seems to me that they've received a verdict of unreliable, weak clean tone, and under-powered. So, how's the preamp? I heard mention that swr released the mo' bass pre as something closer to really being an swr preamp w/ great effects. I've got an swr sm-500 at present, how does it stack up, tonally? And how are the effects, the consensus seems to be mixed?