I finally got around to bi-amping the 4343's. WOW! Night and day compared to passive. I'm using JBL 6290 and 6230 amps for power and a JBL 5234A crossover along with factory 4343 cards. Those JBL's are much cleaner sounding than the McIntosh MC7270 I was using (go figure?).
If you own 4343's, bi-amp them. You won't be disappointed!