As far as I understand it, optical is optical, as one way or the other it offloads all the decoding to your receiver, so if you're leaning that way, I would stick with onboard.
As for choosing between the two, I always go digital over analog if I have the option; you don't have to worry about your computer handling the decoding, there's no signal degradation, and it's one simple cable. That's just my opinion, of course.
|