o.k. have now finished doing the m.f. M6 SERIES, using first the M6I INT. then using it as a pre-amp with the M6 PWR, very nice on both ways, although the integrated is superve on it's own the pwr is greater at low volumes, then tried the integrated for high fqz's and pwr for the bass, i found that the conbination of such was breath taking, not cheap but i am sure that most of other manufacturers products at a lesser price will do wonders to bi-amp, imo, nando.