True, after that it went in another direction. However, the first answer basically had it all: it is the room that you need to be concerned with. Since you ask, I have now found that elsewhere you give the room’s dimensions as 11x16x9 feet, and that makes the subsequent discussion all the more relevant. Room size is crucial information, and yours is very small: it gives a Schroeder frequency of about 200 Hz. Below that, you should expect room modes, i.e. hige peaks and the ocasional dips making for a boomy 'slow' bass. Therefore, if you still want to have deeper bass, you need to open the full box of tricks, i.e. perhaps bass traps, and certainly only small subs (and two or perhaps even four of them) plus dsp room eq. The dipole subs that were also mentioned in the subsequent discussion are another good idea, but probably they are physically to large in that room. But maybe you should just avoid subs in such a small room.
Have you ever measured current in-room response with REW and a Umik-1 calibrated microphone? I ask because below some 200 Hz your main speakers may also need some equalization in that room. For the ultimate solution, there is now the DSpeaker X4 pre amplifier/DAC room eq. But it would be throwing a lot of technology to a problem that is really quite simple: the room is too small for full range reproduction. That size is about the same as my study, and there my choice has been to limit myself to speakers that are great but lack the bottom end: the Harbeth P3ESR. If there is no bass, it cannot get out of control either.
And as I said, even without subs you may already have a problem with boomy bass and room modes. Measure response, and perhaps equalize the main speakers with REW into either the computer if that is your source, or a mini dsp.
If you do decide to go the subwoofer route, the Antimode 8033 is the simplest to use form of dsp room eq, and it works a treat. No need for user adjustability. But it will only work for the subs, and your mains may need something too (hence the expensive DSpeaker X4).
As for the subs themselves, I agree that sealed subs would be better than vented ones. Avoid anything other than the smallest ones.
Good luck. And be prepared for a smallish ideal listening spot. The laws of physics have not changed, even if dsp eq bends them a bit.