CDC Power Status

[VetteRacer]

Is the power for the CD Changer switched or always on?
I just installed an HD Dice and Dice DSP adapter. I tapped into the CDC wires for power on the DSP adapter. When I measured it I had +12V. BUT I was tinkering in the trunk and kept hitting the trunk button for light, so not sure if I was seeing BMWs pre-switched boot power or if its always powered.
Any issues leaving the DSP adapter on that if its always powered? Dont want to drain battery...
Also, does the iPod charge full time or just when car is on? I dont plan to take it out of car, so hate to have it always charging draining battery...

Thanks guys!
Matt
BTW, this is on a 2000 E39 M5