Matching subwoofer

I have a pair of omega super xr3s and they sound like a little more bass would really make them sing. I’m not looking for subwoofer bass but just foundation and stronger mid bass presence. The omegas are single driver 4.5” fostex. My question is how do I know which rep sub would be best for the speakers ? People seem to look at room size and recommend. 7i. I was thinking tzero might just add what is needed. Also wonder if the speedwoofer 10s or rythmic 12 would do just as well. This is for 100% music . Amp is a set 45 by Alan Eaton which sounds terrific.