Hi,
the sub you have is active - ie contains its own power amplifier. You need to take a line level out of the pre-amp (phono socket labelled 'sub out' or similar) and connect this to the phono input on your subwoofer.
Go in to the av32r menu and make sure you have the sub option turned on (in the speaker settings) and then run the test tones to set the speaker levels up.
Basically, you need a phono to phono cable to do this, but other than that you have the right equipment to get this to work.
Cheese