I use a Kenwood car stereo, and the "external device setting" (don't remember exactly the name but that's the idea)can be set up either as "ext in" or as "ipod" (take a look at your stereo's manual it should be similar); "ext in" works for Rockbox, and of course "ipod" is for the OF. By the way, MUCH better sound using Rockbox. Hope this helps.