1961 -- Amazing. You have been the first person that responded to my post, so I did some online research today on my own. I discovered NUMEROUS comments in Forums and articles that said exactly what you said -- the MC225 and MC240 were legendary for being "easy" on their tubes. Especially those original Westinghouse tubes with the "Made For McIntosh" green print. Many people said they were still using the original tubes...60 years or longer. That is just astounding to me.
I dread the day my luck runs out on the McIntosh tubes. Last time I checked, there were still some NOS available at times, but it always worries me when the website says "Call For Pricing". I have thought about just buying a backup set while I can -- I can’t take the money with me! While I’m in a spending mode, I’ve also been looking for an MC240. I have always been told by my older McIntosh owner friends that the MC225 and MC240 are and were the best sounding amps McIntosh ever built. I compared my MC225 to a friend’s MC275 and preferred mine. Maybe it was confirmation bias, maybe not, but I’d like to hear an MC240 in my system.