Is my new amp TOO GOOD?

This is an excellent combination with great synergy.the beryllium can be bright even when breaking in you amp pre amp. Some articles state it takes > than 100 hours to break in.leave the amp and music on low for a wk 24/7. I don't know what cables you have but if they were working on your previous amp they should be OK but some think if you move your cables alot distance wise they need to go through another breakin period . I love macintosh and have alot. Don't give up. I talked to audio classics and they said mcintosh  lasts decades. I would recommend at least 10 gauge speaker wire. The 452 can produce 1kw transients. Worlds best cables from Amazon 7 gauge are great bang for buck.  I have alot of mcintosh  cables that I bought used as it's expensive new. You will love this system in a month.

Mojo771

I don't do any critical listening until at least 100 on any new speakers, and I don't make a final decision until 200 to 250 hours. If you haven't achieved that yet, give it time.

Also I've found when I upgraded to better components, it often reveals other weaknesses in my system. I added an Aric Audio Motherlode XL preamp, and CODA S5.5 amplifier and got a similar reaction up to about 100 hours or so until it smoothed out.

The upgrade however revealed a subtle harshness that was not noticeable before with my older gear, it turned out to be the Chord DAC that I had on a long term loan (was comparing it to my Denafrips Pontus at the time). Better components reveal more, which is not always a pleasant surprise

To @mojo771 -is the C2800 preamp brand new as well?

The larger MC 462 is generally known to be fuller and warmer sounding than the 352 amp overall if you follow regular reports by owners. I'm simply wondering if the C2800 preamp unit is new too, with all new small signal tubes in that as well.  And, as others mentioned before - looking at both units, do both the preamp and amp need at least time to settle in, even though McIntosh indicates no break-in time needed. True or not, give both units at least 100hrs, and I also wonder if you recall your former 352 amp sounding nicer as you got 200+ hours on it, or did it sound exactly the same as new when you traded it in, etc 

Reading all the comments about beryllium tweeters have me sharing my experience.  I have a pair of Revel M126Be standmounts with beryllium tweeters because I found other speakers tweeters to be too sibilant with certain tracks at higher volumes.  I tried several different speakers with different tweeters and the beryllium sound the best to my old guy ears.  If the Revels sounded good before the change and they don’t now you have your answer, it’s the new equipment.  I wouldn’t be thinking about switching speakers to match new equipment although some dealers would love that.  If you’ve given it 100 hours that’s the sound in my listening experience.  Suggest trying different equipment or forget about chasing something new and go back to what works for you.  Best of luck with your new musical journey.  

Thanks for all the input.  It seems like I need to get to work breaking this in. 

Work, work, work, but I will persist.