DVD? I assume you mean AM/FM/CD? I go with iPod (or AUX input), Mp3, or flash drive. Much simpler and I can listen to the satellite radio on my iPhone.
BTW, does anyone really have to say the AM part in AM/FM anymore? Is there a radio that doesn't come with AM??
There are DVD head units with built-in video screens, some of which are 7" diagonal, so maybe the OP would like to watch movies in addition to listening to tunes. I don't know if they make marine versions of these, though. Maybe a remote video monitor?