It might be a good idea to ask if the depression is directly a result of feeling that you are going in the wrong direction, that you are not writing the script for your life that you'd like to write, and that you've lost control of your life -- in which case quitting school and doing something that you are MOTIVATED to do will help lift the depression. OR if the depression is caused in part by homesickness, not enough sunlight, genetic or biochemical factors, neurotransmitters being blocked -- i.e. physiological causes that would be completely unaffected by quitting school.

It might also help to revisit your passion for music and look at the reasons why you wanted to study in the first place. Depression might be taking up so much room in your heart that you've forgotten those things. It would probably be a good idea to talk to a school counsellor - make a couple of appointments if possible so you could look at all sides. and finally, quitting school now, working for a few years and paying back some of your debt doesn't mean you can't go back later with greater passion and commitment.

JTHipster, depression is pretty awful. I hope you get some help as well. Also watch this if you haven't already. It's the best explanation of depression I've ever heard - especially if you have what might be called "clinical depression."