Good idea to swap McIntosh amp stock tubes?

@wbs 

The legendary MC2000, what a great tube amp !  I have always drooled over that amp...  It must sound fantastic !  Congrats !   

Regarding tube wear on my two MC275s in monoblock mode,  I had a full set of Genelex Gold Lion Reissues in them for 13 years.  I tested the tubes, and the 12AT7s (which manage the KT88s) were on the low end of the tester, but, the KT88s still tested practically NOS.  The 12AX7 tests were more inconclusive because I had been rolling them with vintage 12AX7s, but, they did not test NOS, and my impression was that they wore faster than the KT88s.  As you know it is harder to get accurate tests on power tubes vs preamp tubes because they may behave differently under load, so, the power tubes may have been more worn than the tester showed.  My tests were all on a Hickok 539C tester.    In the end, after 13 years, I decided to change all of them anyway, so, I have lots of spares now. 

Note:  I did look up the plate voltages, and your MC2000 is set at 500V DC, while my two MC275 V are set at 450V DC.  With Reissue power tubes, which may not be as robust as vintage power tubes, this may wear the KT88 power tubes faster ?  not sure. 

@emergingsoul 

”Is anyone experiencing very sensitive red lighting when it comes to McIntosh amplifiers? I’ve experienced red light blinking and constant red light conditions and both times I replaced all the small tubes and this solved the problem”

I have on occasion and it was mostly due to bad tubes or tubes getting close to going bad. I have a tube tester and used them to test the power tubes on the McIntosh MC2310 that was red lighting. I found a few power tubes that were below the optimum power range for the KT88 tubes. I tested all of the power tubes first, all 8, and when I isolated the two power tubes with weak power levels, I replaced them with two brands new ones and voila, all was right in the world again. I decided to test the other 8 power tubes in the left MC2301 to see if I was facing a lower power level or other problem with the power tubes. All tested within spec so all good there. The protection circuit in the McIntosh amps are life savers to some extent. I am glad they are integrated into the amplifier system. 

@audioquest4life 

Are older tubes like NOS unpredictable and worth pursuing to replace the mcintosh stock tubes?  Or would more modern tubes be better due to less voltage variations that could trigger red light problems on a MacIntosh amplifier?

You are lucky to be savvy with tube testing whereas my experience has been to replace all the small tubes because it’s difficult to know which one is the problem and I don’t want to start testing them individually using the amplifier because every time you trigger a red light problem it may be negatively impacting the underlying circuit board. Maybe I should start to explore tube testing and be curious to know what device you use.

What small tubes do you like on your 2301?

@hjdca 

Thanks for the nice words about my MC2000.  I purchased it during the sole year of production and have always loved the way it sounds.

I am driving the top half of a pair of B&W N801s with the MC2000 and these speakers are notoriously inefficient so the amp gets driven pretty hard which I have always figured affected tube life.  I got 10 years out of the original power tubes with a lot of high volume listening and thought that was pretty good.  The Gold Lions I replaced the original output tubes with ran for 7 years before one went bad.  The 2nd set of Gold Lions is now approaching the 7 year mark (there was a hiatus between the original tubes and the first set of Gold Lions) and I should probably be thinking about replacements.  But I have never had a problem with any of the small tubes.

Bill

@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.