I need to get more bass from my SF O3s

[Mouse]

I bought a set of 03s a few months back.
In the demo room they lacked bass, and when placed in a different demo room they were very boomy. My salesguy said the room has everything to do with sound, and a bigger room offers better bass than a small room.

When I took them home my bass sounds week, and this room is huge.
My saleguy said that they need to be broken in and will get a deeper sound over time. While this could be true, a few months have passed and it's nowhere as good as the second demo room.

My MC preamp allows for me to set my O3s as "small" but the crossover is 150 hz at the lowest and I cringe when thinking of setting my O3 towers as small.

Any tips on how to get the best bass from O3 towers?