I just went through the exercise of auditioning, the newer Hegel H 400 versus the M33. I was lucky enough to be able to do it in the dealership listening room, but on the same speakers that I own, the paradigm founders 100f.
I also own a Naim, unity nova and I love the streaming environment and application that come with the nova, and so I wanted to like the M33 which has a similar comprehensive streaming environment and application. By comparison, Hegel has a very minimal app. As a side note, I do run Roon, So that does act as a great alternative to a native app for a streaming amplifier.
For me, on those loudspeakers, I found the H 400 by comparison had more openness and airiness in the top end, A wider sound stage with better definition, and noticeably better grip on the bottom end - So I purchased the H400’s.
I’m still no fan of the Hegel app, But if what you want Is the ultimate sound quality and listening experience, I think you have to go with the H400.