I am looking for a RCA select switch so that I can switch playing from my HU to an mp3 device with the flip of a switch. Anybody found a good one? I thought about trying to wire a switch up that toggles them? Anybody done that?

most head units will have a aux input..

Most EQ's have one, $60-$300 depending on the brand. I have heard the little Clarion units are decent, my Soundstream is OK, PPI and AudioControl make nicer ones.

You can get one at Radio shack, I have one but have never tried it on a boat. It's about 3"x5"x1" and has one output, three inputs with buttonw on the front. Should work fine, and better than digging under the dash swappin RCA's! You will have level issues due to the difference in output from the head unit to the MP3 player. <BR> <BR>If your head doesn't have an aux sometimes you can get a pigtail that plugs into your CD changer plug that will give you an RCA input. There is one made for most brands of HU.