Bi-amping Rules

Agree with those who say that you really have to have an active bi-amp system for it to make much sense.  Some benefits can be achieved with a passive vertical bi-amp which of course assumes you are using two identical amps.  Otherwise, you need an active crossover.  In my system, active crossover low passes the bass below about 8O hz to a high power class D stereo amp then to a pair of 10" woofers for each channel; and high passes the mids and highs to a tube amp that drives the (almost) full range drivers. This does introduce lots of complexity and requires lots of outlets and cables.  The system to my ears sounds wonderful but there are many places for gremlins to rear their ugly little heads, which per Murphy, happens on occasion. 

In my case, the music I listen to does not have an overwhelming amount of very low bass content so most of the information is reproduced by the tube amp.  The class D amp is really for all practical purposes, a sub-woofer amp and in fact, the active crossover I use (NHT X-1) was designed primarily to use ahead of a subwoofer. 

there are four descent ways:

1. The best one is not to biamp at all and use single amplifier of sufficient power or monoblocks.
2. Active speakers are usually bi-amplified or can accommodate an external amplifier along with built-in, because they have ELECTRONIC CROSSOVER
3. Replacing built-in crossover with electronic and use same or different amps
4. Mating amps of the same brand with existing passive built-in crossover.

bi-amping my B&W 803Ds, Kebshcul 35W per channel mono blocks on the mids up, and crown 1502 on the bottom end, sounds wonderful, I think the key may be that the crown has input sensitivity, can dial it in.

jrhud, what preamp you're using? And are you using an external crossover? 

I am looking bi-amping my 800D2's.  

When you bi-amp, you become a speaker designer, like it or not.  There was a time when it was a bit of a pig in a poke, but the possibilities were always there.  The miniDSP 2x4 active crossover only costs about $110 and it allows you to do DSP EQ on your system.  No matter the amps or the room you're using, you can measure what's coming out and create a correction filter to apply to the miniDSP.  

This means you can try whatever amps you like and just see how it goes.  When an amp only has a single driver as its load, it can do a whole lot better than you realize.  This also gives you the chance to mix tubes and solid state if you like.  Many have done that with great results.  Tweeters and mid-range drivers require little power.  Most of the power being used in the big systems is lost in the crossovers as well as being used to drive the low end.  And a solid state low end is just so much stronger than most tube amps as well.

Or you can be like most who just prefer to spend many, many thousands of dollars because someone told them they should trust the designers because they charge so much they must be good.  Why should you trust your own ears?