Good choice Razor. There is a coating on the circuit boards for moisture resistance. Sometimes the little cabinets seal different or hardware is slightly different. I run the marine version because mine are under the helm station on the bridge. If I were putting them in the cabin I doubt it would matter much. Lots of guys are having good luck with the five channel MHD 900/5. I have a M400/4 and a M600/1. The new M series are the marine version of the XD series. Very very small size but not much less power. I'm running four 7.7 components and two 10 inch subs. Sounds good.