Mcintosh MC275 alternatives?

That is an interesting, and somewhat incomplete set of criteria--what about price? Why, by the way, those tube types, do you have a large stash of those tubes or are there amps you heard that employ those tubes that you particularly like, and if so, what are they those amps?  If you are not that current with available amps, how did you arrive at the MC 275, and what have you heard and liked or disliked?

Were I in the market for a stereo tube amp made in the USA with more than 50 watts, the Zesto Bia 200 would be my first stop. To my ears, the KT150 tube is far better than the KT88; but if you're into the latter, this amp will take it, with a handy dial control for adjusting bias between tube types. It is more than twice the price of the Mac 275, however. The Bia 120 would also fit your bill, and you could find it used at a good price, but it does not take KT150. Both are pure class A.

Not sure if your still in the market but here's my 2 cents. I bought a used c2200 and used 275x vi both for $6800. They are beautiful pieces of equipment. My dealer had a nice demo room and I brought my speakers in and I felt they were an upgrade from my system at the time. But 2 years later I always felt slightly unsatisfied and I tried rolling the tubes and changing cables. I finally sold  them both. They sold instantly and I made $2000 more than what I paid for(yes amazing). So yes the resale is insane good value. I've read alot of comments/suggestions to get the older 275x power amp, as the vi gen just didn't have the same sound, maybe this is why I was never totally happy. What I did end up with is a tube preamp by Supratek in Australia.  I see someone refer Don's Sachs amp too and from what I know these two are often closely compared. What I can say is the Supratek (Cortese)  several levels above the McIntosh preamp. It's not even close. Its bests it in nearly every category you listen for when critically listening. Most important the music is alive and moves you whereas with my McIntosh i felt as nice as it was at times i never felt moved. One thing is I also use active speakers by ATC so the poweramp is built into the speakers so I didn't have to find a seperate power amp. I swapped the  tubes in the Supratek pre to NOS which make a massive difference. If McIntosh is something you are really set on getting I think it's a safe bet bcs of their great resale value, and I would try to find an older gen 3 or 4 275x I think people are starting to catch on about the gen vi. But I can't recommend a Supratek amp enough, look up the write ups online about the amps which are hand built by Mike Maloney and his LCR phono is magic if your into vinyl. The sound in his amps have gotten some of the highest praise in the audio industry internationally. Its a true point to point wired amp, there is some criticism of his older models being a bit of a spaghetti factory on the inside but this can be common with some earlier  point to point wiring and since then i think hes made a catious effort to make it a  little more organized. The only downside is you won't be able to demo as he does not go thru a dealer but if he did they'd go for many more $. It's absolutely an end system for me and I've lost all interest in searching for anything else. And trust me I'm never satisfied with anything and I'm brutally honest with myself if I'm not 100% happy I have no problems pulling the plug and going another direction even if I take a small loss. But now I just enjoy the music and love the hobby and appreciate reading otherws experience or sharing my experience. My last piece of advice, good audio system with reputable names sell, so you can try many different options if you are a smart shopper without losing your tail off. Best of luck on your journey.

No backorders on MC275s if you buy from overseas suppliers LOLOLOL

https://www.aliexpress.us/item/3256804259732450.html?spm=a2g0o.productlist.main.17.4b5f560a5hQxf3&algo_pvid=f6f18372-6ae8-44ff-a03c-d4bc0ee5f068&algo_exp_id=f6f18372-6ae8-44ff-a03c-d4bc0ee5f068-8&pdp_ext_f=%7B%22sku_id%22%3A%2212000029205889276%22%7D&pdp_npi=3%40dis%21USD%211920.0%211708.8%21%21%21%21%21%402102160416763782296836942d074f%2112000029205889276%21sea%21US%210&curPageLogUid=S8aT5rmVXyL0

There is a pair of McIntosh MC75 amplifiers currently listed on the Audigon website. They are restored, but a lot of people find them to be better than the MC275 amplifier. I have MC275s and love the sound. They've improved with upgrading the input and power tubes.