Good idea to swap McIntosh amp stock tubes?

Tube amplifiers that reflect sound changes when tube swapping occurs may not be designed very well.

A bit of an obnoxious assertion / wording on MC's part. It's true that if a circuit design runs its tubes in an egregious way (e.g. way out of spec, or far from optimal conditions for a given tube type), then tube rolling can have much more sonic impact than normal. But I've always found that tube rolling has audible effect, even in well-engineered components and for slots that have been advertised to "not" reveal tube rolling differences (e.g. cathode followers, grounded grid outputs with SS CCS).

I think one of the most frustrating things about this situation is that McIntosh installs tubes that are questionable as to how good they are.  I believe the consensus is they are not as good as they probably should be. They put their fancy logo on each of the tubes and somehow that’s supposed to make them perform better.

Does anyone believe the tubes used by McIntosh are good? And then they have a problem if we try to change the tubes because they have designed their amplifiers based upon tubes that may not be as good as they should be so they advise against changing out these tubes.

This is very annoying and really shouldn’t be. I have no idea how to evaluate the quality of their tubes except from other people are saying and many many people are saying they improve upon the McIntosh amplifier when they swap out the tubes and the people saying this are fairly seasoned in their abilities when evaluating an amplifier after all their customers of McIntosh - people who know how to evaluate sound quality I would hope or better at it than most. So clearly respectable views and yet the tube quality installed in the amplifiers is still less than what people feel comfortable with.

I think one of the most frustrating things about this situation is that McIntosh installs tubes that are questionable as to how good they are.  I believe the consensus is they are not as good as they probably should be. They put their fancy logo on each of the tubes and somehow that’s supposed to make them perform better.

Does anyone believe the tubes used by McIntosh are good? And then they have a problem if we try to change the tubes because they have designed their amplifiers based upon tubes that may not be as good as they should be so they advise against changing out these tubes.

If they’re JJ-sourced, then they are not good. JJs go right in the trash. Chinese tubes can be extremely bad or very good (and everywhere in between), depending on source & screening. Russian tubes are generally good to very good.

When you have very selective large tube suppliers / buyers like Upscale Audio and VAC - who completely avoid JJ tubes - that says a lot. The only reason many use JJs is price and availability.

And there are definite reasons why a brand would want to discourage tube rolling "experiments". 

I have used the stock McIntosh tubes in my C2500 preamp since I bought it in 2017.  I only changed the MM phono tubes to Gold Lion tubes because I once heard static.  You have plenty of options for tubes with your amps. The McIntosh branded tubes (JJ) are good enough for people who don’t visit here.  For people like us, we always want better.  I have never had a McIntosh branded tubes fail and the stock tubes are not crappy tubes.  It sounds to me like one of your amps has a problem if one of the tube LED’s intermittently keeps lighting up.  Did you buy new or used?  Do you really think McIntosh uses questionable tubes with all the tube equipment they produce?

@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.