Subwoofer Suggestion

Hi guys I need your suggestion regarding subwoofers. My system is composed of Focal Kanta 3, Kanta center, 706BK it would be used 50/50 for music and HT. My room size would be 13m by 4m by 3(Length,width,height). Would it be better to go for dual pb1000/sb1000 or single sb3000 or single pb2000 or single PSA S1500?
I just added dual Rythmik L22s to support my Tekton Pendragons, and I’m very happy with the sound after weeks spent integrating. As stated above, consider rolling off the mains. I use a K231 active crossover at 70-80hz, and this creates incredibly powerful and tight bass from the subs, while allowing the mains to offload the lowest freqs, which cleans up the entire midrange. This method is challenging, and it can sound weak down low until everything is properly dialed in and integrated. Then you have deep bass, clean low-mids, clearer voices, and a sense the bass is truly emanating from the same world as the rest of the music. It’s labor intensive to dial in, but I found it way better than running the mains full range and reinforcing with subs, which led me to different flavors of muddy midrange. This is very system/room dependent, and may not work for you, but hope it helps! Getting bass right makes everything better.
@kulo The REL T/9i retails for $1299 USD. But in my experience you can buy them (I bought two) for a discount from a dealer in the US. I don’t know where you are located. 
I'll give this a try thank you.
As stated above, consider rolling off the mains.

king baracyda I'm located in Philippines, everything here is so expensive compared to US.
Thanks ieales I'll check the prices of martin logan subs here thank you.