Is my new amp TOO GOOD?

These are all great suggestions.  OP, please report back in a couple weeks and let us know if things have settled for you.  I've had this same situation with gear.  And sometimes it isn't burn in.  Some gear makes some of my favorite music sound rough maybe because the extra detail can rob some songs of their warmth.

Would love to hear how this story winds up for you!  Best of luck!

When you had the MA-352, did you use the 8 band EQ?  The C2800 takes that feature away.  Consider adding a Schiit Lokius+ in between pre and amp. I’m sure this bothersome brightness varies with different recordings. Your newly more revealing system is maybe just telling you like it is, and you are blaming the messenger. With judicious application of EQ, you can edit the message. 

Your speakers are very detailed revealing sounding and are known for their excellent sound imaging but tend to reveal every detail and with the upgraded McIntosh gear your sound is leaning on the harsh side. McIntosh pairs better with Sonus Faber speakers which are much warmer sounding compared to the Revel speakers that you have. If would consider Sonus Faber speakers as they pair very nicely with Sonus Faber. But if that’s not an option I would consider swapping out the C2800 for a PrimaLuna Evo 400 preamplifier. This will give you a warmer less harsh sound with your Revels. 
 

I was considering upgrading to the exact same McIntosh gear you just selected so this thread caught my attention. I currently use Sonus Faber Olympica Nova III speakers paired with a Parasound JC5 amplifier and P6 preamp. My next move was between the PrimaLuna preamp at $6500 or the McIntosh gear you chose for upwards of $20,000. For cost reasons I’m going to start with the PrimaLuna preamp first. 
 

Excellent advice from everyone else here that I have read but I honestly don’t think upgrading a DAC, longer component break in or better speaker wire will make a significant impact on what you are looking for. 
 

Summary: Try PrimaLuna tube preamp if you love your Revel speakers, or consider Sonus Faber or other warmer less revealing speakers. I hope this helps.

@mojo771 

I’m wondering if it’s the tweeter in your speakers. Years ago I bought a Hegel H390.  I then bought KEF Reference 5 speakers, partly because Hegel used them at trade shows. When all was said and done, for me it was an awful paring! The metal Q drivers made listening almost painful and relatively low levels. I then bought a pair of PS Audio Mono blocks with a tube input section And a PS audio signature preamplifier also with a tube input section. The KEF speakers sounded better, but still were too bright.  About a year and a half ago, I went back to paper and silk drivers and bought Sonus Farber speakers. I can now listen at whatever level for however long I want. 
I’m not familiar with Revel speakers.  What are the midrange drivers made of and what are the crossover points?

All the best.

After everything is nicely run in there is one more important way to control HF.  Speaker rake (speaker tilt front to back) is a very effective way to add or decrease the amount of treble you hear.  Enjoy your new equipment!