I ran a small memory wire directly to the battery and have had zero problems from it even when stored for 4-5 months. Stereo memory draw is only .007ma, so on a typical boat battery of 800 cca it will take 4762 days, or 13 years, to drain the battery to zero. At that point you should've sold the boat anyways.

50 milliamps is what my alpine drinks , it will take the spring out of the step of one deep cycle in about 3 months.

I ended up buying the JL Media Master. It does have the eeprom feature. Not hooked up yet, but it appears to be a little easier to use (intuitive) than the single din Sony it is replacing.