I'll agree, the Cube amps, with COSM effects, sure seem to sell well. A lot of people like it, worth looking at. There's another little one, ZT Lunchbox... about 8" square and 200 watts. That one has sold really well lately in the store I frequent

Gotta scroll down to see it
http://www.porthuronmusic.com(Link content may change since I think it's a featured product page)
Just Google ZT Lunchbox if it changes.
It'll surprise you. If all you need is an amp with tube sound, this is another one worth at least trying out.
Don't laugh, I'm serious.