I find this thread interesting as I'm about to embark upon a biamping expedition myself. I have two beautifully refurbished Yamaha m2s. I plan on building a electronic crossover with burson op-amp replacements. This crossover will cross over at the mid-base mid-range crossover point of 400 cycles which is exactly what my speakers use. That way the amps will work in their sweet spots, my preamp is an anthem str and will automatically cross over to the crossover to the two amps running my founder 100s and to my sub xr13. I think the external crossover is the answer to this problem for the original poster. Someone mentioned a Dayton DSP which I believe is just a rebranded mini DSP which would do the trick because it would create a crossover point. Allow you to adjust the timing and allow you to adjust the levels for each amplifier that has a good chance of succeeding. If each amp has level controls this is definitely a must try. All the people that say this is a fruitless proposition. Forget that as audio files everything we do is a an experiment in our constant search for audio perfection. No experiment is fruitless if it increases the knowledge that you have about reproducing sound in modern systems, that is just the journey that we take. I've been doing this since I was 16 and could drive myself to my local audio store and set up a friendship that lasted through my teenage years. Go ahead and hook them up. And balance them and see where you stand. You can always unhook them and go back to the old way. Try them forwards and backwards. You never know what you're going to hear. Have fun!