I have seen a couple of threads re a splitter for taking the single RCA cable that comes from the amp and changing to the two inputs on the sub. A few questions, is this important to do? If it is not split is there a downside (and if it is split is there an upside?)and where should you plug the single cable in (L or R?) Also if it is better to have the two inputs where can you get the splitter bit from?