I'm guessing you're using a JBL BP600.1 as a sub amp?
How does a Blueprint BPD 1202 look with a pair of 12" PR's? The sub is 2ohm DVC and can be wired in parallel for a 1ohm mono load to the amp, so it'll get 600w.
BTW, they're $97 from
www.audioliquidators.com.