A good sub to mate with Focal 1037's

I haven't owned a sub since my Sunfire, some 7-9 years ago. I'm looking for a sub to integrate with Focal 1037's. I'm sure there has been a lot of improvement from that of the Sunfire that I use to own. Budget would be up to $2500. Thank you in advance for your input!
Check out the REL subs, very musical!
I agree with Jafant. I use a Rel B3 with my Focal 1027 BE's ... very fast and musical. Keeps up nicely and disappears easily. TAS has a great review of it and it is in their recommended list.