I use the same cab and speaker combo as ghunter with my RK1. It's a great sounding cab and I've been very happy with it. No complaints at all.
I'm considering getting one of Avatar's 1x12 cab specials for another amp that I have, but am torn as to whether I should go open back or closed (for a different sound) I have a little 5/15 watt combo amp that has a 1x10, but really opens up, sounds louder, and is so much more full with a 12" speaker.