hey I have a set of M-Audio BX5 monitors that I use 80% of the time just to listen to music. I'd like to add a powered subwoofer to give it some kick. I don't want a reference sub, and I will isolate the sub when doing any mixing anyhow. I can get a sub at wholesale from work easily, but my problem is how to interface it... I have a set of composite stereo outputs (the old red/white) going to 1/4 inputs on my monitors. What would be the best way to add a sub (with a composite line input) in the chain? Any input would help. thanks!