Possible to use active x-over with integrated amp?

I have a Peachtree Inova integrated amp. I was wondering, is there any way to high-pass the speaker outputs on the Inova? I'm using the system with a subwoofer and would really like to use some sort of active crossover so i can ease the power requirements off the main speakers, and not have them produce the bass frequencies under 80hz. I don't know how I would go about doing this though, or if it is even possible with the Inova. Anyone have any ideas?
Two methods. Use a passive high pass filter consisting of a capacitor in line between the amp and preamp. Not the best solution, but it does work.

Second, if you don't mind purchasing another piece of gear, you could get a miniDSP.