Help with vertical Bi-Amping

John is right. You are actually talking about horizontal bi-amping. if you cannot find identical amp, you will need an active crossover.

thanks guys, guess I wasnt thinkin far enough outside of the box, by the way how complex are active crossovers, and what all is involced with speakers, do you need to Dig inside of speakers and change the internal crossovers? thanks again Chad

One point that is often over-looked is the reduction in IIM distortion (interface intermodulation distortion) when speakers are biamped. This includes passive biamping with the speaker cross-overs. The speaker is not just a "motor". It is also a generator. It is constantly feeding spurious energy back into the amplifier. This energy is generated by the moving mass of the speaker drivers exiting the resonance peaks. Some of this energy is dissapated by friction as heat, some of it is fed back into the amp as a back EMF. The woofer with the most mass generates a lot of this energy. ANY non-linear component that this back EMF and the audio signal both pass through will result in cross-modulation products. When you bi-amp, none of the back EMF from the woofer can cross-modulate with the mids and highs; only with the bass. If you have ever experienced a burst of grating distortion that seems to coincide with certain bass notes you probably have experienced this kind of distortion. There is a very good discussion of this in the current (May) issue of AudioXpress.

Behringer digital crossovers are very popular these days for bi-amping. One of these units would go between your preamp and power amps. Some of these crossovers have XLR connections, which will work fine if you have balanced equipment. If not you will need adapters or wires that are XLR on one end and RCA on the other. You need only disconnect the internal wires to the speakers from the built in crossovers, and in turn run wires directly from the amp outputs to the individual speakers. You can re-attach the old crossover wires later, if you want to restore the speaker to it's original condition.
If you decide to horizontal bi-amp, and use the amp that you have for the top, then you will not have to get the exact same amp for the bass drivers.

Thanks for info, if speakers or bi-wired then do you still have to bypass an internal crossover sperating the low and highs is done already from biwirw posts, or am I mistaken?