McIntosh Guy Going Tubes? (Maybe?)

I agree with tlong1958,
I have a C2500 with Genalex Gold Lion tubes and an MC452 and would not change.  I used to enjoy a C50 and when I received the C2500, there was a small, but noticeable change in the "musicality", especially voices and acoustic instruments; when I swapped out the stock tubes for the Genalex, those qualities improved even more.
The MC601's are such great amplifiers!  I personally would not change those out.

I could not accommodate a pair of MC601's so I'm running an MC452.  I believe both amps have "the best of both worlds", the "warm" sound that usually goes with tube amps, but the "speed" of solid state.

The only problem I can see with going to a C2600 with Gold Lions might be the stress on your facial muscles...controlling the "jaw dropping" response when that preamp breaks in!

tlong1958,
One of my audio buddies swapped out his MC452 for one MC275 and found (for him) it didn't have enough "horsepower".  He purchased a second MC275, running them each as a "monoblock" and that put a smile on his face.  Being retired and using his system several hours per day, he's now complaining about the cost of replacing tubes on the MC275s.  One thing to think about, when going to a tube power amp.