I am really new to the world of nicer computer audio and I'm looking for a little guidance and where to go. I have a 2007 Macbook Pro, Behringer MS40 Monitors, and a Dayton 10" sub. What do I need to make this work properly. I ordered a Griffin Firewave to work in the short term, and while it works it is finicky to set my sub to a reasonable volume (I live in residence so bass volume is important). Basically I am looking for a reasonably affordable way to use both the speakers and sub, and hopefully independently change volume of both. Thanks for any help.

Bumping for help. Would something like the M-Audio MobilePre USB work for me? I really have no idea, and that makes searching for answers difficult.

I would look for an external dac with an optical input. Im assuming your looking purely for sound quality. Did you have a budget in mind for the new gear?