I'm by no means qualified to give any advice on the mix, but have always had issues with getting good tones out of amp sims (generally too thin or boomy and lots of EQing needed).
Then I got IK's Axe I/O which made a huge difference in getting good solid tones (at the initial gain stage). Now my amp sims sound like they're supposed to. I highly recommend it if you're a guitarist or a bass player....it's the closest thing to a real amp.
Hopefully, someone will chime in on the mix.