A buddy of mine had both of these. He decided to keep the 20s after comparing them. IMO, the Stuidos are a bit too bright for my taste as well. The Studios need plenty of power to bring out the best in them, as they are relatively demanding speakers. Not so much the 20s, but the 40s and up, but the 743 should be able to handle them, and the warmer nature of NAD should offset some of the brightness. My buddy was using a NAD 753 to drive his 20s and he said it was a great match, but swapped it out for a B&K recently.
See if these shops will let you bring them home and give them a listen. That's what I did with v3 40s. I had them for a week, and found that they weren't right for me.