Do I need a subwoofer? Which brand and model?

Interesting...a few observations:

1. You have an exceedingly large space...that will challenge many systems to provide serious bass/impact. Presumably you know this already. After all, you live in the space and know how much volume it takes to really drive that room with impact.

2. Bass impact comes from [simplistically] two places: a) the ability for your main speaker AND amp to wallop you in the upper bass, and in the case of your speakers perhaps teh mid bass as well. So a powerful amp here [may help]. Sometimes, adding mass damping to the top of your speaker can help a little as well...try a 20kg weight on top of each speaker (preferably not iron due to magnetism issues)...and see what happens

It also comes from lower regions which can be enhanced by a sub when set up well. Surprisingly, a classical recording often has very low bass signals that give you a sense of the recording venue/space...in my case, i drive a Velodyne DD18 with Wilson X1/Grand Slamms...and when you shut the Velodyne off, the sense of space collapses and you have 2 speakers in front of you with a soundstage behind them...vs around you.

3. If you can try a high powered (high current) amp even for a weekend, i would be curious what happens to your upper bass slam. If you can try either a Velodyne or REL, i would be curious as well

Hope that helps a little. YMMV. Good luck and pls continue to post questions...

Several good brands are available on-line and offer a free in-home trial period. I'd agree with Lloyd that your space is large and that a subwoofer (or two) would likely improve the tonal balance of your system, but a free trial allows you to satisfy yourself.

One very appealing offer comes from SVS (svsound.com), which shows a pair of sealed 12" subs for $950 (last I looked). The SVS subs have an excellent rep, and a pair of subs is likely to get you smoother in-room response than a single sub. If you do want to stick to one subwoofer, you could check out Rythmik (I use two and am completely satisfied) or HSU (another brand with a good rep).

Thank you Lloyd. I will try a more powerful amp if I can get one. Good suggestion and thanks for the detailed explanation on the physics.

Marty, I have researched the brands you suggested. My options are a pair of SVS SB1000, a single SVS SB2000, a single Hsu VTF 15H or ULS 15, or a single Rhythmik F12.

The Hsu VTF 15H or ULS 15 are the best deals at the moment - a Black Friday special.

I would rather buy a single higher end now and add one more later.

Please let me know which one you think fits my need the best - my needs are musical rather than movies.

Lloyd, When you suggest a more powerful amp, what level of power should I consider? My NAD 365BEE is 80W per channel. I could consider something like an Anthem integrated amp at 225W per channel. Should I consider other brands or wattage as well? My spend comfort is around 2K. Thanks again!

I have OPPO BDP-105 , I think you will be happy with HSU-VTF15H. I am very happy with this.