FWIW:Why? You are currently running the best there is with NOS GE being pretty equal as well. They will last a loooong time in those amps.
Your quest for 350B's (Valve Art makes a nice one) might yield sonic improvement in those amps, but the current draw is higher in the 350B. @ 1.6A vs .9 for a 6L6GC. It would put some strain on the PT, not sure if it'd be too much.
There are some nice new issue tubes that sound glorious in these amps - Tung Sol 6L6G Coke Bottle & Tung Sol 6L6GC STR Black plates being two of the better examples. Though I have NOS RCA & GE stashes, I actually prefer the coke bottles in my MC30's. In my MC240's I love GE & RCA.
Brave is the man who tries to outdo McIntosh at its own game.
As my grandfather used to be fond of saying, "When in doubt...don't."
Cheers.
After owning the MC30 for sometime now, never looked back for selling my 2015 MC75. The level of musicality of MC30 is in an another league by far (to me). BUT, for some of you are looking for modern Hi-Fi sound, MC30 is not your game.
This thread has strayed from 62caddy's original post. Hope it hasn't been hijacked to far.
One thing that bothers me is why McIntosh does not reissue those wonderful amps?
Why? You are currently running the best there is with NOS GE being pretty equal as well. They will last a loooong time in those amps.
Your quest for 350B's (Valve Art makes a nice one) might yield sonic improvement in those amps, but the current draw is higher in the 350B. @ 1.6A vs .9 for a 6L6GC. It would put some strain on the PT, not sure if it'd be too much.
There are some nice new issue tubes that sound glorious in these amps - Tung Sol 6L6G Coke Bottle & Tung Sol 6L6GC STR Black plates being two of the better examples. Though I have NOS RCA & GE stashes, I actually prefer the coke bottles in my MC30's. In my MC240's I love GE & RCA.
No problems with reliability for me. If you bought from a reputable vendor - not eBay- you'll be fine.