I was looking through some pics and saw this and it looks to be a small amplifier for the 6 inboat speakers. To me this is a step down from the kicker our 2008 moomba had. Here's a link to what I believe is the amplifier.
http://greatlakesskipper.com/product...amplifier.html
This is a pic I found of the amp in a 21v.
http://i85.photobucket.com/albums/k5...e1/21vamp1.jpg