Someone who has heard at least one of these...

...but hopefully both...your opinions. Let's assume they are the same price or, maybe, only $100 difference.

The REL T7 subwoofer vs the Sunfire SDS-12. Both are new and come with the warranty. There really isn't a way for me to hear these with my system in its environment at home.

Speaking of, that's a 20x20x13 Media room and the electronics are a vintage B&K St-202+ Sonata amp, a matching B&K Pro-10 MC Sonata preamp (both from 1993), an OPPO Digital BDP-105 as the source, and a pair of Monitor Audio Silver RS8's from around 2006.

If you have heard one or the other sub, or preferably both, what say you, if the price is that close? Also open to other suggestions for a sub still, though I am getting down to the nitty-gritty here and my wallet is starting to itch...

Oh, last but NOT least...this system is used almost entirely for its audio capabilities. It is very rare I use it for any HT applications. I do know that makes a difference.

Thanks for you help!
I would hands down choose the REL! Because of the versatility in connecting it. REL makes subs....that's what they do, period.