I bi-amp my passive crossover speakers (B&W N803's) because:

1) I process the bass frequency signal (under 400 Hz) coming from my pre-amp with a parametric EQ. The room/speaker interaction has been analysed with the same True RTA program that SH has refered to in many posts. The EQ adjusted signal has to be the single most important improvement to the sound quality of my system.

2) The EQ'd bass signal is also limited to a 600 Hz ceiling (low-pass filter) so the amplifier is dedicated to low frequency signals only.

3) The amplifier serving the mid-high frequency speaker driver circuit is fed the full (non-EQ'd) signal, so the internal crossover does all the work. True RTA has shown that I do not need EQ for the mid-high frequency range. Since the midrange and tweeter transducers provide most of the spatial and subtle tonal information, I have chosen not to include a processor in this signal path. I could pass the signal through a high-pass filter, so the amplifier does not need to boost the full bandwidth, but I have concluded that this is not as critical. The actual current demand for the mid-high circuit is relatively small.

I am not against active crossovers , as I have used them in live concert venues. This is the way to go when professional musicians are plugging in to a complex chain of processors and mixing boards in a live environment. Typically live music processing is quite different, and does not have the same spatial information as the studio engineered sound found in recordings.

Many who work in a studio environment (SH is certainly one) prefer to use monitors that emulate those found in live sound venues. I am not sure, but I would guess that movie sound editing would benefit from systems that are based on those found in large theaters.

There are, however, a very significant number of highly regarded professional studios that use the passive crossovers found in the monitors themselves. The studio space and audio systems are all professionally analyzed and balanced by the recording engineers to provide as "neutral" an environment as possible for the type of music (varies for classical, jazz, rock...). This list includes Tellarc, Deutsche Grammophon Gesellschaft, Abbey Road Studios, etc... There is no expense spared in these studios and control rooms.

[This message has been edited by AGAssarsson (edited May 15, 2004).]