If you're recording AND mixing down, I'd recommend better monitors. Those monitors are great for rough-tracking (if you're an artist recording your own stuff). 'Cause most guys then take their stuff to a studio for mix-down. If you ARE the studio, then you'll want something with a bit more clarity than those.
That, and maybe a better LDC mic in the mix, but I really think it could be your monitors (and finishing your room treatment). Hope that helps.
EDIT: I'm adding something else here ... and MAN I hope I don't sound like a jerk 'cause that's not my intent. I listened to that song, and honestly now I think you may need some more time behind the desk. There are some things that could be done to that mix, in regards to EQ, reverb, compression, that could really improve it. The vocals are a bit weak on the mids and the electric guitar part in the beginning is really small-sounding, and crunched. This may be further proof that you need a better monitoring system, but I think it also comes down to just doing MORE mixing and getting a better feel for things as you guy. I hope that isn't discouraging or anything. I mean it all constructively. I will say that there are parts of the mix that sound good. It's not a crap mix at all ... just needs massaging.