"I agree with Unsound. Not only is it unlikely both amplifiers would have the same gain, but they will also have different characters and this will occur at the crossover point. Speaker manufacturers make every effort to develop a seamless crossover. Why mess it up?"
How is the crossover point messed up with passive biamping?
Simao: As long as you're careful, there's no reason you shouldn't play. It's fun to experiment. You have adjustable gain (re: Unsound's objection) anyway. You'll probably learn a lot in the process. However, I do agree with Sandstone that your mids will likely miss the Sophia. Maybe just incorporate the Velodyne with your Sophia and Triangles, and remove the Onkyo?