I'd turn your gains up. Remeber, your putting out max power at 80% on your volume with a 0db test tone. You'll never see full power out of your amp on music, ever, not with that setting. Sure, you'll never clip, but it's like having a ferrari and then putting a govenor on it and wondering why it's not going fast. If you don't want to set by ear use a -6db test tone. You'll see quite a bit more power out of your amp, you will only clip slightly at high volume trasients meaning at high volume levels with bass heavy music, but unless you plan on listening to really heavy stuff all the time (like a 0db test tone) you wont' clip. It's much more realistic for the intended purpose of the sub (playing music).