Subwoofers I have not because Duos not go low enough, I actually measured them go down to 18-20 Hz. It has more to do with the optimal placement, in doing that for approx. 2 years, I have realized, that a main speakers placement optimal for imaging is not always ( as in never) coincides with the optimal bass reproduction
That forced me to use an active crossover and cut off Avantgardes at 80 Hz , everything below that is handled by stereo JL subs.
An overall improvement has been immense. I have come to a conclusion , that this approach is probably the only correct one.
In your case, I don't think the smaller room could accommodate Mezzos