professafresh

Long story short, I have gotten my hands on all 5 surrounds and the sub from an HT-SK5 HTIB setup. I didn't get the Samsung receiver that came with it, instead I went out and bought an Onkyo TX-SR304. The only problem is the sub is passive, and there's no builtin amp on the receiver to power the sub. The only sub I'd like to use the either optical or coax sub outs on the receiver. Can anyone recommend an amp that'll work with this subwoofer and/or some sort of connection method? Thanks in advance.