What kind of inputs and outputs does your sub have? A high level connection uses the speaker wires, a low level connection uses the RCA plugs into your amp. Need some more info for a proper answer.
Pre amp to sub hookup, or speaker level?
If my pre only has one set of main outputs, how do you recommend hooking up a subwoofer? Is it better to use a Y adapter and split the signal out of the pre, or run a second set of speaker wires from the amp? Is it ok to run a second set of speaker wires off my 2 channel amp, or does that interfere with its main speaker driving duties? Thank you