tube rolling Mac 275 mk IV

I have had a Mac 275 mkIV for about a year, and would like to try a few new tubes. This has been my first foray into tubes and do not have any experience doing this.

I am currently using original Mac supplied tubes, and would like to hear what has worked well for others. The rest of my system is comprised of a Modwright 9.0 SE pre, Ayre CX7 cdp and SF Cremona Auditors. I appreciate the comments and suggestions.
I also have 275 mk IV and SF Cremona Auditors. While I never listened to the original McIntosh tubes as I bought the amp preowned, I did compare the Valve Art cryo tubes vs. Svetlana SED KT88's. The SED tubes are much more dynamic overall. The Valve Art tubes sounded more like classic tubes with very warm midrange and rolled off highs. The Svetlana SED are very good tubes for the 275mk IV, which in itself is a fantastic tube amp. I also own 501 monoblocks and switch back and forth and enjoy both tremendously.
Genalex KT88's work very well with my mc275, go for the GEC model and save a few hundred on a quad. Telefunkens and bugle boys will work well with the 12ax7 and 12at7, many choices there depends on your budget. Get rid of those stock chinese mac tubes and your amp with come to life.
Thanks for the responses. If I would need to upgrade the tubes in stages, would I be best served replacing the '88s first or the 12ax7s and 12at7s?
If its in your budget try replacing the 12at7 with telefunken ecc801s first, I noticed much better top end with improved resolution and clarity.