NAD vs. Adcom

Don't over look B&K amps. I recently heard one and was impressed given money spent.

No comments on the possibility of the NAD Silverline S200 amp [probably in conjunction with the S100 preamp]?

I'd guess the bi-amping with such dissimilar amps may be the 'problem'.

Almost any single more powerful amp will help. A good integrated which can handle the B&W load, not just impedance but phase angle as well, is recommended.

Maybe a NAD in the 37x series? That is, if you like the NAD house sound?

One of the M series integrates would work like mad, but the cost may be a little brisk.

BiPolar? MOSFET? Good bad exist with either device type. If it works well with your speakers, don't let either deter you.