Single vs. Dual Subs

Properly integrating a sub is really hard work, and rarely done by 90% of those who buy a subwoofer.

Technically, correct! I would even go as high as 100%. But 90 will do. Which is why I always and only recommend a DBA with 4 subs. Try and do it with just one and you are doomed to failure. When even the guy who uses one knows it is really hard work, and even then works only rarely, everyone should listen. 

And then go out and get more subs. To do it right. 

My listening room doubles as living room so sub placement was dictated by furniture. Even so the Audiokinesis Swarm sounded fantastic out of the box. I am sure I could fine tune it if I had a dedicated room but this is already wonderful with minimum effort

I am currently running two subwoofers. It’s not talked about much but the biggest improvements come in mid range clarity And the highs have a little more pop also not to mention increased soundstage and detail. I also found out that the best sound that I got was from stacking my subwoofers so don’t be afraid to experiment !!!

Okay, so if going with dual subs, can you mix and match sub brands? Seems like sticking with the same driver size may make a difference. I have a Paradigm x10 but was thinking of pairing that with Sonus Faber sub to pair with my SF speakers, but I might be better to go with a second x10. Integration with the same brand seems obviously a lot easier.

"Seems" and "is" are two very different things, for sure when it comes to subs. Duke makes his Swarm with plugs enabling you to convert one or more ported subs to sealed. After studying the matter and talking with Duke mine were made with two ported, two sealed. I also have a 5th sub that is ported iso-baric.  

The truth of the matter is there is no "integration" process with a DBA. You plop them down, you set the levels, they are "integrated" whatever that even means. To me it means the bass is seamless with the rest of the sound stage. This happens automatically. You could use five completely different subs or five all the same, no difference. So save your money.