Yes, the boost only works on the clean channel. Try some Mesa tubes. Use color code blue or gray. They should work fine.
As to the 2X12 cab. I had one for a short time. I found it kinda weird. It sounded good if you stood in just the right place. But overall I thought it was kind of thin sounding for a 2X12. Not really what I expected. I liked the 3/4 back 1X12 much better. But I like a darker tone, so depending on what your after it may work well for you.
