Do I need a subwoofer? Which brand and model?

I mainly listen to classical and jazz - mostly trumpets and violins, with the occasional piano, viola or bass guitar. A couple of my friends have been suggesting to me that my ensemble lacks bass and having a subwoofer will address it. My setup includes a 2 ch. NAD C365BEE integrated amp, Wharfdale EVO 50 loudspeakers (pair), and an Oppo BDP 105 Bluray player as a CD player. The setup is in the living room, with three walls, and the fourth side open to the dining room. The living room itself would have been 18' L X 12' W X 18' H = 3888 cu. ft, but the fact that it opens up to the dining room makes the entire space more like 40' L X 18' W X 12' = 8540 cu. ft. Would I benefit from a subwoofer and which one should I get? Budget $1000 or close to that.