I recently bought 2 sets of db 651's and put in my boat. They sound good until I turn them up loud on a hard hitting song they sound horrible. Just a bad sound. How can I fix this problem.

Glad to help! Make sure that you purchase an amp install kit with that amp. It will give you the needed power cables, fuses, connectors, instructions to make this work for you. Important to use adequate power cabling/fuses to protect your boat's electrical system. Let us know if you need any more help. I have installed system in my last three boats and it does make for a more enjoyable time on the water.

How can I fix clipping?