Actually, I had an M33 and now have an H390. Here are my experiences.
My thoughts about purchasing an amp were much like yours: The M33 has "great reviews" "bonus looks" and Dirac (which I really wanted). The M33 sound was really nice -- but -- in my experience, not the software that ran it. I needed a very open system to feed it. Bluesound, to my great surprise is rather closed. You must have NAD equipment to use it (at least for WiFi connectivity). Marketing literature clearly caught my eye and I convinced myself that would give me what I wanted in system architecture and sound. The NAD is built carefully and certainly looks really impressive too. While literature said: "Just connect speakers", I fought hard to get their software to work -- for weeks. <ugh> Their software support people were great I must admit.
I have, for good or bad, a pc with JRiver Media center. After sharing my plight with my dealer, and telling him that I would supply the network hardware and software to feed it, he recommended the Hegel H390. He also had Martin Logan 13s at home (mine are 11a’s). Unsure, I ultimately decided to not be bound by that eco-system and turned the M33 in and bought the H390.
So many people have commented what they prefer that I continued to be worried about making the right choice and wasting even more time and money instead of enjoying my purchase. After turning on the H390 for the first time, and playing the same music as with the M33, my head kind-of snapped: Where did the speakers go? What kind of sound is this? OH MY -- I LIKE IT!
And there you go. Everything works as advertised and I am happy (and relieved!) in another world of wonderful sound that I never imagined.
- Hank