I have two suggestions that come in right at your price point ($2K):
Magnepan 1.7 and Monitor Audio Silver Series 8.
I auditioned the Magnepans powered by an NAD C 375BEE and it was a good match--smooth and natural, it let the Maggies show off what they are about. For impedance matching and tonal balance, your C 356BEE should sound similar, but you'll be missing a little bit of volume potential. However, while the C 356 is rated at 80 wpc (into 8 or 4 ohms), they have a lot of headroom built in, so they should cleanly hit peaks 3dB above that cleanly. You could get those 1.7s and possibly be happy with the C 356, but I don't know your listening tastes and your room is medium-largish. But there's no harm in getting them and checking out the match. Worst case is at some point you might sell the 356 and move up to the 375, which I *know* is an excellent match with these speakers.
I have had my Maggies for exactly three years, and they still so captivate me, continue to pull me into the music, and reveal natural-sounding music reproduction that I still think of them as my "new" speakers. None of the "new toy" novelty has worn off. In fact, the way they've gotten better with extended break-in and the more ways I notice how well they do so many things, I look forward to listening through them as the months and years pass.
I've also heard an earlier version of the Monitor Audio Silver 6 and Silver 8. They are more sensitive than the Maggies, and should be able to hit clean peaks of 107-109dB with your current NAD amp. These have excellent tonal balance, transparent midrange, smooth, even, extended highs, good bass reach, etc. They also look very nice. If the bass overloads the room, you could plug or attenuate the ports with rolled up towels or something. Or you could go with the Silver 6 with less bass output. I'd personally go with the Silver 8 because it has a dedicated midrange, is in your budget, and you can attenuate the bass by plugging one or both ports.
Stereophile review of earlier version
Magnepan 1.7 and Monitor Audio Silver Series 8.
I auditioned the Magnepans powered by an NAD C 375BEE and it was a good match--smooth and natural, it let the Maggies show off what they are about. For impedance matching and tonal balance, your C 356BEE should sound similar, but you'll be missing a little bit of volume potential. However, while the C 356 is rated at 80 wpc (into 8 or 4 ohms), they have a lot of headroom built in, so they should cleanly hit peaks 3dB above that cleanly. You could get those 1.7s and possibly be happy with the C 356, but I don't know your listening tastes and your room is medium-largish. But there's no harm in getting them and checking out the match. Worst case is at some point you might sell the 356 and move up to the 375, which I *know* is an excellent match with these speakers.
I have had my Maggies for exactly three years, and they still so captivate me, continue to pull me into the music, and reveal natural-sounding music reproduction that I still think of them as my "new" speakers. None of the "new toy" novelty has worn off. In fact, the way they've gotten better with extended break-in and the more ways I notice how well they do so many things, I look forward to listening through them as the months and years pass.
I've also heard an earlier version of the Monitor Audio Silver 6 and Silver 8. They are more sensitive than the Maggies, and should be able to hit clean peaks of 107-109dB with your current NAD amp. These have excellent tonal balance, transparent midrange, smooth, even, extended highs, good bass reach, etc. They also look very nice. If the bass overloads the room, you could plug or attenuate the ports with rolled up towels or something. Or you could go with the Silver 6 with less bass output. I'd personally go with the Silver 8 because it has a dedicated midrange, is in your budget, and you can attenuate the bass by plugging one or both ports.
Stereophile review of earlier version