Adam Sub8 or Sub7 with A3X

[Jan [MTW]]

Hey guys,
I own a pair of Adam A3X about a year now and I really want to upgrade the frequency range of my setup. I want to do this to be able to mix the lowend, which I really just not hear at the moment. Also this is kinda for enjoyment, since it's just way more fun to listen to music on a setup with a subwoofer.
(Yes, I just could buy some hifi-speakers + subwoofer for 100€ but that isn't my main point, so this is out of the question).

-Basic acoustic-treatment is already done
-My room is small (4.25m x 2,85m)

I assume the Sub7 would be the better choice, since the Sub8 is ment to be used with the A7X? Or would the Sub8 still be better for my setup?
Or does a setup with the A3X + Subwoofer completely suck anyways, because the A3X have no subwoofer which is ment to be used im combination with them?

Thaankz!