A friend of mine asked if he could run a Wet Sounds WS420 on his boat without using a head unit. Even though I've always used mine with a head unit, it made me realize that I didn't need the head unit at all because I just plug my music player directly into the WS420. I really don't use my head unit for anything! It really opened my eyes to the flexibility of this unit for ATVs, golf carts, etc. I'm assuming similar units, such as the Kicker ZXMRLC, would work the same way.
Maybe this is common knowledge and I'm just clueless, but I wanted to pass it on.