Reference strada one or two subs?

I currently have the reference strada side speakers on floor stands and a rel t1 subwoofer. All driven by a rega brio-r amp. Love the sound just maybe lacking a little bit in the low end. Wondering what adding another sub might get me. Any one have any thoughts?? I'm too poor to go for the reference 3.5s but hoping to get some good advice on how to improve the setup. Many thanks!
Just posting some followup. I raised my cutoff to 110hz and repositioned my sub right center and properly coupled it to the floor beneath the carpet using spikes. Also moved the right strada into the corner, approx 1 foot from the back wall and 1.5 feet from the side wall. Wow! Much better integration. Bass is improved on the strada and bass from the t1 is just subtly less boomy. The combination is awesome! No doubt I'm going to go for a second t1 for the left side. Just wondering if anyone has had any luck getting a better floor coupling with their strada floor stands? The spikes don't work that well for carpet and they still seem to rock a bit.
I replaced the original spikes with "carpet penetrating CP1
Bearpaws" (their name) from a company called edenSound
( I had them drilled for 1/4" x 20 studs. Only
problems are (1) the studs go into the Gallo stands only about one-quarter
inch, (2) the studs are only 3/4" long, so shearing them is a potential
problem, and (3) they still rock a little because the footprint of the stands
isn't that large. But they do an excellent job of reducing resonances I used to
be able to feel by touching the stands. They couple better and they look cool

Total cost for 6 of these brass spikes incl. shipping was something like $240.
I suggest you read my detailed review on the Rel Strata and you might just get some ideas to experiment with.

Hope it helps, if you have any questions or require clarification drop me an email and I would be happy to share my knowledge further with you on the Rel.
Thanks guys for the advice and help. I will check out your review and hope it gives me some new ideas.
Definitely two subs, unless the one is powerful, critically-damped, and dead center. Raise your crossover to even 120-150Hz if possible. Set the subs for stereo bass and high-pass the Stradas if you have the option. The Stradas are incredible, but they get nowhere close to 40Hz, you'd have to get the Mapleshade floor stands for that.