Good idea to swap McIntosh amp stock tubes?

@emergingsoul 

I would not emphatically state that NOS tubes are more prone to failure vs modern tubes. It comes down to manufacturing quality and reported performance of NOS and modern tubes.

I use the Maximatcher tube tester, both; the power and preamp/diode testers. 
https://maximatcher.com
I think it is a very useful tool to use if you use tubes in your system and very helpful when trying to isolate a bad tube. 

Many people swear by NOS tubes but I have had experiences where the tube equipment may just burn through those type of tubes because it is built to extract the maximum power or signal from any tube and for whatever reason, poof, your NOS tube is gone and hopefully not your equipment.
 

Now, modern tubes, can exhibit the same characteristics; however, they are newer and are built to nearly the same standard as the NOS tubes. For example, I have used Siemens, RCA, and Telefunken 12AX7 tubes in my Aesthetix IO Eclipse and while they all sounded good, eventually, I would run into the errant symptom of a tube whistling or popping. The Aesthetix IO drives the 12AX7 tubes hard I believe. I swapped in modern Sovtek 12AX7LPS and am happier due to less down time and worry about a tube going ballistic while also sounding good. I would rather spend less time and money on tubes so that I can enjoy the music more and not worry about fiddling with tubes for the sake of trying to experience the equivalent of the aurora borealis in my system. 
 

Not sure what power tubes your amp takes, but the Gold Lion KT88’s have a great track record with many McIntosh tube amp owners. The GLs seem to work well and sound great with the McIntosh amps. I have over 10 years of experience using those tubes in my MC2301’s and have swapped all 16 tubes twice with only about 4 or 5 tubes failing during that time. I previously purchased about 15 years of power tubes based on roughly 3-5 year swaps. I still have the OEM Mcrintosh, and some JJs, Sovtek, and Mullard as backups in my tube collection. 
 

@chickenoregg 

"MC275 = 2 channels @ 75Watts @ 8ohms"

Ah no, the above is at 1Khz and not 20Hz - 20Khz.

"If you were responding to me, let me be clear that I didn’t say they came with poor quality tubes. I said they were fine but don’t sound as good as NOS tubes. Respectfully, I don’t think I’m the one that’s being misleading. 

Were I you friend, I’d be careful where you throw rocks when it comes to who has knowledge and who doesn’t. You blatantly quoted the wrong spec for an amp that is named literally for how many watts per channel it has, and then started hurling rocks at me while you called me a dummy. 

I swear I couldn’t make this stuff up if I tried."

You know what's hysterical? If you look at the posting date and time, you'll see that we were typing at the same moment and I never saw your post! 

@faustuss 

My bad. Let me make that up to you.

Here's a code for all the free JJ tubes you might ever want: 5687. It's an in-store only promo code though, so you'd have to drive to my shop to use it. When you arrive, make sure you park in the back. After you've entered the code, make sure you kind of tug on the lock hard enough (sometimes it seizes up with whatever kind of disgusting ooze the crackheads have slobbered all over it) otherwise the dumpster won't open and you'll have wasted even more of my time.

sooo.. based on couple of of “tube experts” opinions, conclusion is a McIntosh engineering design team is clueless when the time is to pick tubes? LOL

JJ tubes (former Tesla) are just fine, just need to test them properly, before plugging in, as any other brands. I have Luxman state of the art MQ88uC amp, and replaced original Luxman tubes with preselected JJ ones, without any problems, measured / listened! 

I’ve owned the 275 and currently have the 1502.  In my experience, the stock tubes are not the best.  In both amps, the Sophia Electric KT88s were a huge improvement.  I’ve been using NOS Mullards for the 12ax7 and 12at7 for years with no issues.