MC275 Tube Rolling...

For the KT88s the best I've found, and reasonably priced are the current production Genalex Golden Lion KT88. They are vastly superior to Russian Lyting "C"s, Electro Harmonix and the stock McIntosh tubes. There are several online sources for the Genelax tubes. Then, add Herbies tube dampers (to all tubes) to reduce microphonics and you've got a really dynamic, rich tube set. For the 12AT7s and 12AX7s you can't go wrong with either Mullards, Telefunkens or Amperex Bugle Boys. The Shuguang triple mica have also been recommended to me for the small signal tubes but I've not heard them.
I realize that McIntosh uses the stock tube sources to insure production supply continuity, but the tubes I mentioned above will transform the MC275 and bring it to an entirely different (superior) level of performance.
The 275 can also be further improved by setting it on three Mapleshade Heavyfoot V3 brass footers.

Another insight is to match your 12types during purchase. Whether you select Mullards or Telefunkens just make sure the vendor tests all the tubes as matched pairs. Same goes for KT88 you want a matched Quad of KT88/6550 regardless if it's NOS Genalex or GE, JJ/Telsa Blue Glass, Electro Harmonix, EAT, or SED.

FYI. Last year I knew nothing about tube rolling. Nothing!! But I was forced in to action because I started to hear popping sounds from the stock tubes and then my fuse blew days later.

Several phone calls later and hours reading on the web (GON and tube sites) I had answers to my questions.

What is your preamp and loudspeakers?

I have a Silverline Sonata MK I. I am planning to go with a Mac C-220. I have to tune it as the sound is now not what I want, and I am trying hard to find out what tubes, which brand, what production will have what affect in what area... I am excited to know what you guys have settled down with and why... More input is definitely appreciated!

Lapierre makes an excellent point about matching tubes. Sound advice to follow.
I'm using a McIntosh C2200 as my pre and it is a great match for the 275 so I think your interest in the c220 is well justified.
I started on the tube-rolling path when I noticed my stock KT88s were pulsating blue light. It was weird because you couldn't see it looking directly at the tubes only out of your peripheral vision. I thought it was just my aging night vision until my wife noticed it, too. The stock tubes don't last more than a year, if that. But even if they're still good you will be rewarded with rolling to better tubes.

I have re-tubed almost all of the smaller tubes (12ax7's and 12at7's) with telefunkens. I was a bit skeptical about how much sound improvement I would get but I certainly did hear a better difference. While waiting for a second set of tubes for my 2nd Mac 275 (I have 2 running in mono) I could distinctly hear the difference between the right and left channels (Telefunkens vs stock tubes).
I have yet to replace my KT88's but plan to do so.

RWD
Rick