Yes it's RCA. You should be good at 30 feet. I've got RCA leads at least that (likewise, for a surround sound system) and can't notice the loss in quality (there should be some, being analogue). I'm certainly no audiophile though.
Reading around suggests quality degrades a bit after about 25 feet, but it seems most people are referring to rca in video signals. For audio, you should be ok.
edit: Bear in mind you'll need to avoid sources of interference. I didn't mention that previously.