Let's see what kind of subs and voice coil impedence setup he's talking about before we make the hasty assumption that this'll fry his subs. He says he thinks they're pushing 600W; doesn't mean that that's what they're capable of handling. Nor does it necessarily mean he'll wire them at 1ohm on the Memphis.

And even if it's a 1100W wired to feed the subs that handle 600W, you can always set the gains down. It's not set in stone that you HAVE TO turn the gains up. Like rcurley55 said, just use common sense and you'll be fine. I've run a 250W RMS sub in a temporary setup for months off a 1000W amp and it never blew cause I wasn't stupid enough to crank it up full blast - I just set it reasonably.