Of the amps you mentioned, I have heard two and they are very different. ( Hegel and NAD) Great, but different. Unfortunately, it was an apples to oranges, different dealers and rooms listening. I have a real soft spot for Hegel and not for NAD. The NAD is supposed to be a Purify, but I was not impressed. Maybe all the digital stuff in front. Don't know. Maybe I like the distortions from the Hegel. They were on Wilsons which are pretty good. I heard the NAD on B&Ws which I do not like at all. Don't get me wrong, both are serious great units. Just my preference.
Your weakest link, kind of stretching to call it weak, is probably your RIAA stage.
Do look at the actual bitrade of the files you are streaming. They may not be as good as you think.
Have you considered an outboard DAC? I am not sure the Hegel ( or NAD) internal is as good as it could be. Not bad, but not great. I auditioned the Hegel with a Qutest, the NAD with it's internal.
Room correction can be critical, but do you need as complex as Dirac? My room is too bright and being a LIVING room, no treatments are forthcoming. I put an Antimode on the sub ( single family so I can run a sub) but on the mains, I find just a traditional tone control to balance very nicely. My speakers are pretty flat in free space. I could do that in JRiver, but I find some CDs I need to adjust a little so for now, old school tone control for the treble. Your brain will "pattern" the room and unless things are really bad, fix a lot of EQ issues. You get used to it, or as the subjective reviewers say, the "electronics needs weeks to burn in". Really, it is their brain adjusting. Dielectrics form in hours, not weeks.