When this thread started, almost two years ago, I was using a BP6, Since, I've tried several non-Bryson preamps, including a Parasound , Nad and Cambridge. Coming back to Bryston, I invested in both a BP-26 and a BP17 cubed - - - and upgraded the amp from a 4B SST2 to a 4B cubed. (Thiel 2.7 speakers plus an SS2.2 Sub)
I only listen to classical RedBook CDs, and, for me, the BP 17 is all I'd ever want. Every now and then, I get the feeliing I'm back in the Great Hall of the Musikverein, listening to the Vienna Philaharmonic.
Conversely, my son, more into Jazz, Contemporary, R&B, Country and Rock, clearly prefers the BP-26. I guess it may be the slight mid-bass boost. He likes it, but I think it slightly distorts the lower mid and bass. (No, I don''t need hearing aids.)
In either way, in his opinion and mine, we prefer the Bryston preamps - - plus the 4B cubed.