Nad M3? Need amp for Vandersteen 3 $3,000 budget

I have those speakers and have used Bryston 3B-ST and Quicksilver V4 Tube Mono Blocks. I have recently settled on Red Dragon M-500 Class D Mono Block amps. The others were good in their own ways but overall I prefer the Red Dragons. Clean, powerful, great extension in treble and bass. Very reasonably priced.
Another option is finding a used Audio Research 100.2 or 150.2 which also were quite nice. Good luck.

For rock music, I will suggest an used Theta Dreadnaught 5ch, disable the center channel and use the other four to bi-amp the Vandy 3A.

Ayre Acoustics uses Vandy speakers to "voice" their amps during design/development, so they are a natural and often-used pairing. Ayre V-5XE amps are available secondhand for $3K.

The NAD M3 would be punchy, substantial, and powerful with a large and deep soundstage. Smooth. Probably not the last word in air and high frequency detail but that could be a good thing if you have a reflective listening space. It also has tone controls and I did not find their effects objectionable but unnecessary. Around $1400.00 or less used. I would've kept mine but I like to have a larger display so I can see the volume before I start a song.

The Belles 150A Reference is a great amp with Vandersteen.
I've been using the older 150A Hot Rod with the current model 2Ce Signature 2 with great results. Matching the Belles with a tube preamp is a great classic combo..