I'm getting a subwoofer in a little while and will be using speakers that I already have. The subwoofer I have is a passive one with only a "fork" wire, one purple and one black. I know that I will have to use some sort of amp to run the rca out from the receiver to the amp and plug the sub into the amp. My question is this....what is a good, yet cheap, amp to look for ? All the ones I've seen so far have several outputs for speakers, often a left and right speaker output. Which would I put the sub wire into ? Also a short side note.....I've been reading that you can plug the wires of a passive subwoofer into the front speaker outputs of a receiver. How would you do this and would it really work ?