If you want a small sub I would suggest the Ep400, it has an astounding sound to it and blends very well, just not very powerfull for HT duty, really meant for small rooms. I can also recommend a Paradigm DSP3100 a little more oomph than the EP400(marginaly), not a whole lot bigger and has a similar sound to the Axiom sub line up.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70