Your next purchase (after the C1000s and line transformers) could be an AD-20 and an NJB3... but I wouldn't know anything about that.
Matt's right about keeping your MD after you upgrade. You never know when it'll come in handy!
Seriously, if you want to hear C1000 > AD-20 > NJB3, I've got a Blues Traveler show I'd B&P for you.
Chuck