I'd look at Premier speaker cables at www.interlinkhouse.com or else email the designer, stnemo@starpower.net. He once recommended Premiers to me, for a similar goal to yours: they can carry a lot of current. One thing I'd bet the rent money on: they're worlds better than any AudioQuest cable. I've had both, though in a lower-power system than yours.
Bass speaker cables
I have an active bi-amped system. I am using Krell KMA-160s on the bottom and am looking for a good speaker cable for bass response. Does anyone make specific cables for lower frequencies? If not, what cables are recommended for the best bass response? Most of the system is currenty Audioquest or AudioTruth cables.