MC901 monoblock tube matching Q

Thanks for the replies, all. In addition to the MC901’s I’m also running a C1100 (tube preamp). One of my tubes is microphonic, which got me thinking it might be a good idea to keep a spare set around (especially considering the Russia situation).

From some quick research, I get the sense that power tubes (KT88) should be matched, but that signal tubes (12AX7 & 12AT7) don’t necessarily need to be matched. Does this sound right to y’all? Although the language in MC901 manual makes it sound like nothing needs to be matched in those amps, at least from my reading of it. So, I’m a bit confused.

I contacted McIntosh and was transferred to their Parts Department, who informed me that "he’s pretty sure" the power tubes (KT88) should be matched and the signal tubes (12AX7 & 12AT7) do not need to be matched. Not confidence inspiring.

Nice the dream team 901's and C1100

My understanding is all Mac tube amps use a biasing system that obviates the need for matching either power tubes or pre-drivers.  But sourcing your tubes from them should be the safe bet. If their parts guy doesn’t inspire confidence, ask one of the more senior tech advisors like Chuck Hinton. 

Looks like @crustycoot is correct. I called McIntosh again, this time got Chuck in technical support. He said neither the power tubes or signal tubes need to be matched in their amps or preamps. He did say it’s possible there may be a slight audible benefit if using matched sets, however. Guess that answers my questions. 

Get yourself a couple of spares,and call it a day. Sit back,and enjoy the music.