Rsync, sync, and other programs of the like won't work with the empeg. The built in file system uses a database for the songs ... it's not something that you will be able to sync to without an empeg specific sync tool.

A good question is just how much power does the wireless access point (or EC) actually draw from your 12V battery? Do they actually go into a power saving sleep mode when not used for a period of time?

The real answer to all of this doesn't really involve the serial port at all, save that for the GPS device. Use the wire that was meant to do what you guys are talking about ... The amp-turn-on lead ... Even if the car is off, if the empeg is on, so is the amp turn-on-lead.

I wouldn't run the power straight off of that line, but I'd hook up a simple relay (I'm no EE, but they're easy enough to use) to listen to that line, when it goes dead, cut the 12V power going to your access point.

Greg