Yeah, what 2x6spds said. Use the big amp to power both speakers. The other 2, I'll do you a favour and take them off your hands
Seriously ... I'm not to familiar with Mac amps and their sonic characteristics. What I used to do when I had 2 amps (Bryston 3B and NAD C370, both 120wpc), I used the one with better imaging to drive the highs (Bryston), and the one with more 'slam' to drive the lows (NAD). The thing I dislike about bi-amping with dissimilar amps is, the images tend to 'shift'. For example, the location of a piano (off centre) moves depending on which amp is driving it!!
Try it for yourself and tell us which setup works best. I don't think anybody here can comment for sure until s/he have heard the results.
Good luck!
