Okay I'm in search of a new battery that will not only start my engine but also run my vs player and 500w amp. I have a 17 foot winner escape, with a 3.0/4cyl OMC cobra. I want to be able to start it whenever but also play my stereo while anchored. Should I use a starting battery and a deep cell with a switch, or just run one dual purpose battery? I was thinking dual purpose was the best route, but I'm not sure. Any suggestions???