Your experience of moving to two subs

@gladmo Assuming your 7T's have a fairly flat frequency response down past 50Hz fugetaboud stereo.

The only time I didn't need to use the crawl test (you don't actually need to crawl but it won't hurt to do both walk and crawl) to map out my listening rooms bass mode / standing waves was when I used four subwoofers. Once you've mapped the room you'll know exactly, or at least near the optimal subwoofer/s locations.

There's a rub. Your going to need some long interconnects to do the crawl test and most likely a longer pair for the location. You don't need anything exotic. Blue Jeans Cable custom makes economical cables for this purpose.

Since both your subs come with a modicum of equalization you can adjust them individually to your taste then use the one with the remote control as the master to control the volume of both. You'll most likely run them together at a lower volume. They absolutly do not need to match. Good luck with the reward.  

One man's datapoint.

Hsu VTF2 Mark IV subwoofer. (Out of production.)

In TV system: one sub off to one side opposite main speakers but not in corner..

In audio system: four subs behind main speakers.

No difference between one sub and four. 

Subs make your main speakers sound better because they don't have to work as hard with the sub handling low bass duties.

This Hsu sub has two ports which I have plugged with the foam plugs that come with the sub. Less bass but tighter compared to leaving the ports open.

https://youtu.be/_7ZGLrOpCQo

https://youtu.be/xUMDlpVu98w

One sub is fine, two are always better. More is better in the case of subs. As others have said, multiples really can better fill out the sound stage and give a really full and balanced experience. One huge fallacy is that subs are for movies and not music. That is an opinion that is completely baseless, proven wrong consistently, and only held by insane "2-channel only" types and possibly deaf sheep herders.

What sounds good to me is what’s optimal in my system.

For me, the saying is,

What sounded good to me is what was optimal in my system, until I learned about how to improve it.

While I don’t want to be on an endless hamster wheel, this is a hobby for me precisely because I am striving to see if I can make things better.

I have been able to improve the sound in the past, and that motivates me to keep trying -- because it’s fun, not because I have a "grass is greener" dysfunction.

@dean_palmer said
“That is an opinion that is completely baseless, proven wrong consistently, and only held by insane "2-channel only" types and possibly deaf sheep herders.”

I say….

Thank you making me howl. That is so freakin’ funny!