Now I have a reasonably good understanding of speakers and electronics although I am pretty much a novice in the world of High fidelity. So I am looking at buying a stereo amplifier but am a little confused with Bi-amping. No I understand passive crossovers are not as affective as active crossovers as there is a small amount of distortion at the crossover frequency or something along those lines. However as I understand the use of active crossovers is not widely practiced in the hifi world so what is the purpose of bi-amping when using passive crossovers. Also do I need two amplifiers or do some stereo amplifiers offer the ability for bi-amping? My price range for a used amplifier is around £150-200, and I currently own a pair of B&W Dm603 S2s. Also I was wondering why active crossovers are not used in hifis? I was thinking when using a sub which I would like to, surely having an active crossover take away the harder bass frequencies from the main stereo speakers and give it to the sub would reduce the strain on the main speakers and give a better sound? Also using an active crossovers when Bi-amping would surely remove the inherent disadvantages of using passive cross-overs?