I have biwired (actually, triwired) cables simply because they came with the speaker (I bought my Linn 5140s and cables from a friend who bought Vienna Acoustic Beethovens). When I bought my Mirage speakers, also used, they also came with biwired speaker wire (which I'm now using to power my Linn 5120 center channel, also -- you guessed it! -- bought used).

If I buy the 770, I'll have 4 amps doing nothing for a while. I figure I can test biamping to see if it makes any difference at all. I already have the cables; I just need to modify them a bit. If biamping doesn't make a difference, then there's no loss. If it does make a difference, then I might keep the speakers biamped.