small speakers

I don't think the power of the NAD would be a problem with the JB3. I've tried them in my main system and driven them with both a 15 watt Class A tube amp and a 50 watt solid state amp and they sound even better in there than they do in the office. The efficiency is 87 db so they need a little power to sound their best. In fact, I've been thinking about using the NuForce Icon as a DAC and preamp and inserting a more powerful amp into the system to push the JB3's a little harder.

Spendor S3/5 speakers work very well in a room of your size.

pro-ac tablettle III will be good choies.

The Ascend Acoustics Sierra 1 gets really nice reviews and I think can be had at or below your price target -- that would be my choice if you're buying new. Minuets are great too, but you can probably get a pair of used SR17s in your price range that would offer far superior performance. I'd take any of those over B&W at that price point, but that's me. Best of luck.