A used Musical Fidelity a3.5 integrated should work well for you. I had the a3.2 and a308 in the past and they sounded great with jazz. I listened to an a3.5 when they first came out and it was markedly better than the a3.2 to my ears. It would be a noticeable upgrade from your NAD and would be an amp to build future upgrades to your speakers and/ or source should you desire.
I see there are two for sale now on Audiogon. I have no connection to either seller.
I see there are two for sale now on Audiogon. I have no connection to either seller.