Subwoofer for music only ?

Bass get’s directional because of the overtones. A single sub prevents the Imaging directional Bass creates.

Thus, my preference, IF subs, use a front facing stereo matched pair, located adjacent to your primary speakers. When a pair, smaller subs can be successful, easier to fit.

Subwoofer Ports: I am not a fan, if so, front facing.

A major reason to use sub-woofers is so you can use smaller primary speakers WITHOUT ports in them, (which exist always to get more bass from drivers that cannot do it by themselves). Adding a stereo pair of Subs, then the primaries do not need ports! You might try blocking primary ports when you add subs (another reason to use two). Better to plan the combo of primaries with no ports and subs together initially than to add subs later.

My main speakers, 15" woofers, when designing the new cabinets, with the help of Electro-Voice Engineering (they were still in NYC then, and extremely helpful), we calculated tuned rear ports, to eke out a speck more from the 15". A youthful and wrong headed experiment I realized. In prior space, no wall behind them, the ports were a slight asset. Moved here. rear wall too close, I blocked the ports.

IF anyone buys speakers or subs with rear ports, I advise at least trying them blocked, make a decision.

I use this 3 lp set to evaluate bass, adjusting my speakers, evaluating cartridges, ...

The Bass, 3 LP set, Excellent Performances as well as Famous Bass Players

btw, a pair of self-powered subs, pre to sub/equalizer, bass to sub, upper bass/mid/highs ONLY back to amp is a very good method of trying tubes, because less power is needed from the amp, thus more affordable, lighter, less heat, increased location options.

And, the smaller drivers will sound cleaner because they are not trying to do what they really cannot do.

btw, square rooms can be problematic, perhaps others here can tell us how they solved square rooms.

and, for Video, Small Home Theater like mine, I use a single sub, just to get things like Jurassic Park Dinosaur Stomps, Black Hawk Down ,,,,, Room filling Impact, not directional unless you have a large Home Theater, then, a pair!

13 by 13 is a small room... After the king size bed, dresser and tv go in, you may barely have room for a microsub such as the KEF KC62. However, It is a more technologically advanced sub that’s better for small room music than your subs listed above (will integrate better, more extension, etc). It is twice the price, of course.

A subwoofer that can’t get down below 20hz is not a subwoofer, just a woofer. Higher standards is key!

Deep_333, I have a queen bed and no dresser. Bed against rear wall that is sound proof wood slats and stereo against front wall. I had a Paradigm sub I placed under the foot of my bed and it died recently. I'm only using for music, No TV in bedroom.