I've just ordered these speakers, but I'm a little confused by the cable that connects the 2 speakers together: A couple of reviewers have said it's an aux cable, but it looks more like a single RCA cable in both the pictures and videos I've seen. I'm probably going to need a longer cable than the one supplied, so if someone can confirm if it's RCA, or 3.5mm Aux, that would be great. Thx.