Using a ICEpower 1000A by itself?

No problem as long as the PSU meets the specs listed in the data sheet. I recall that ideally you have a low voltage supply of a little more than the +/-12V that is standard for the A-series (see the data sheet) but otherwise no problems. Oh, and of course the 1000A isn't full-range output, but as subwoofer-amps they should be great 🙂