Hooking everything up for the first time

If I'm correct, it sounds like you are trying to use the pre-amp in the receiver to feed the power amp? If so, you need a regular IC from the pre -out jacks on the receiver to the input jacks on the amp.

>using the pre-amp in the receiver to feed the power amp?
Yes.

I'm guessing 'regular IC' is an input connector? I don't have any or know what they are, I didn't think of that when I bought the stuff. Can I not use big fat speaker cable?

No, you need a regular IC with rca connectors. Not sure how you could even use speaker cable...

No, do not use speaker cable.

Purchase a standard analog interconnect with RCA plugs.

Same type of interconnect that you would use to connect a CD player to a receiver.

Rich

Looking at the rear of the Onkyo: http://www.jr.com/onkyo/pe/ONK_TXNR515/

It looks like you have a 'Pre Out Subwoofer' and a 'Line Out Zone 2' at the bottom, a little left of center.

Hook a set of interconnects with RCA ends from the 'Line Out Zone 2' into the power amp inputs. If that doesn't work, try the 'Pre Out Subwoofer'.

Chuck