Fest,
Here's a pic of the little box I made for my boat. It is basically three pac lc1's in a box. In other words it is three dual potentiometers. They connect between your head unit RCA outputs and your amps. If you can plug in RCA's you can install it yourself.
I put mine in a piece of 1x2 rectangular aluminum tubing that I had left over from a light bar I made. I did that because I wanted to make a standalone unit that I could stick to the bottom of the dash. I had an anodized aluminum faceplate made for it. The letters are engraved and can be any color you want.
I also put a port for my Ipod shuffle in there so I could have a removeable 20 hrs of music that won't ever skip.
It doesn't require any power or ground connection, just the RCA audio connections.
Depending on where you would want to mount it, and what other controls, jacks etc. you might want on there, I could make you something in an enclosure like I made or a faceplate with the controls mounted to it that you could flush mount somewhere.
It's just something I do for a hobby, build stuff for myself or my friends when I can't get what I want commercially or want something different. Cost of something like I made in an enclosure would be around 150$, something simpler like a flush mounted plate with audio controls for three separate sources would be more like 60-75$ depending on how fancy you wanted to make the engraving, what material you wanted to use, etc. for the faceplate.
