replace Mcintosh with Luxman

My Magico S3MK2 are powered by 2 Luxman M900u amp (using C900u pre-amp)
without knowing your room i can almost assure you you will get improvement in all aspect 9more refined sound, more dynamic and micro dynamic, plenty more details and control over the speakers)
a friend of me have the same combination (Luxman 900 series amp & pre + Magico S3MK2) but also Mackintosh MA 9000 he use to power his focal speakers on the other room.
one day we switched the amp just out of curiosity, so we powerd his Magico's with the Macintosh, the Luxman combination was far better to our ears

I have a better product for less if you don’t mind having to see the meters , the Excellent Coda CSIB integrated amplifier stereo timesgreat review ,best of 2020
for $6500. The best integrated under$10 k 
and better then any separates made in USA  10 year warranty
and powerhouse 3,000 va potted, not open transformer 
Mc ,or lux man 1/4 the size and 3 choices for power 
the lowest 150,300,600 has 18 first watts in pure class A.

Hello,
I would call both manufacturers and ask them if the other brand works well with their product. Also, talk to a dealer who is a dealer for both of those products. They might say it works great or give you a better option. Make sure you let all the people know as much information as possible. Type of music you like. Size of room
Do you have subwoofers and how are they connected. 
Treated or untreated
The cables that will be connected 
All of this information makes a big difference 
I hope this helps. 

I question how much of a difference you'll get with replacing a nice pair of mono blocks with another pair of nice mono blocks?  Maybe the preamp would be worth a second look?

I think it would absolutely be the right way to go for me. :)

However, if you are happy with the Mc sound especially in the high frequencies you may find the Luxman to be warm by comparison.

Luxman's are neutral, extended, and have a magical midrange.