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.
shugho
Bob, I did check that I am using the dedicated stereo outputs on the Oppo. Those are separate outputs entirely from the 7.1, so there is no room for confusion.
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I have been standing in the middle of the room, about 4 ft away from the speakers, dancing in delight :) Ordinarily, I would sit 8-10 feet away on my couch. I could adjust them a little I suppose, to accommodate the normal listening position.

I ordered a SV2000 subwoofer right now and will let you know how that improves the situation!
I just have to add this because I'm THIRLLED. There is a sweet spot that can be achieved. I have found it by moving things around - speakers, furniture, myself. Having found it, I am going through my collection - Bach - Julia Fischer, Hilary Hahn; Barber, Corigliano. Chris Botti. Everything sounds AMAZING. This is what I have been pursuing for a while. I am in HEAVEN.
The 4 ft separation is the best I can achieve given my room, I ran into space issues with my furniture and a fireplace on one side. The important things I did was to bring my speakers out far enough in front such that there is nothing barging into the sound (such as a sofa that partly impeded the sound cone, if you will - I am referring to the area the sound may emit into). I then angled them more towards each other (say roughly 35 degrees from the center line). If I stand roughly 4-5 feet from the speakers on the horizontal straight dividing them, or closer, I get outstanding soundstage, which varies as I walk close to the speakers in in interesting way. If I walk back further than 4-5 feet, there is a drop in soundstage. I am trying to adjust the angle now to bring the sweet spot closer to my sitting position, which is a good 9.5 feet away from where the speakers are at the moment. I am ordering a SPL meter to make this a little more scientific - saw a product named Galaxy Audio CM 140 on Amazon. This is cool stuff.