How to hook up a powered sub to Exposure 2010

Run a pair of rca terminated interconnects from the pre-out connection on the back of your integrated to the low level input on the sub.

Since you're using both an Exposure integrated and the Exposure power amp I'm assuming the pre-out connection on the intrgrated is already in use to connect it to the power amp. Yes?

An alternative, since the Exposure power amp has two sets of speaker outputs and the Totem has high level-inputs, would be to run a pair of speaker cables from the second speaker outputs to those high-level inputs on the Totem.

That second set of cables doesn't need to be of the same gauge or quality as your primary cables since it's sending just the frequency and amplitude information for amplification by the sub.

Why do you have two stereo amplifiers for a 2.1 system?