I've been nosing around looking for more DRC options, and I found Fidelify, a program that looks promising for integrating spotify. It allows the use of VST plugins like ARC system 2 to be used on the spotify files. Also, it's in beta, so it think the download is free. I might try and work with it a bit later tonight.
Here's a link for those interested:
http://www.fidelify.net/