TSM-MM not loud enough ...

While I have no problems with bass due to integration with Vandy 2Wq subs, the TSM-MM can not fill my 21'x16'x9' room. It has taken years to get my system as optimized (to my tastes) as it is now, other than lack of shear volume at times. Is there any viable option? Would the VSM fill my needs? I think Merlins are in my blood forever, but ...

Any input appreciated.