Re-tubing a McIntosh power amp

not rolling but upgraded from stock, oh baby what a quest.

stock tubes from whom, OEM tubes or you bought used? I imagine OEM's put what they believe is best, then people replace/roll. The difference to the OEM of 'stock' tube cost is insignificant to the cost of the amp.

You will get into the issue of Bias, I started a thread about that 1-1/2 yrs ago, after ton's of advice, then Covid, all kinda other new stuff all over the house, did nothing about bias.

https://forum.audiogon.com/discussions/tube-bias-socket-to-me?highlight=bias%2Bsocket%2Bto%2Bme

Since 1973 I have messed with these power tubes: EL37's; EL34's, 6L6; 7581, 5881; 6550, KT88. weak, shorts, got hold of some money, .... a variety of amps and reasons.

Most recent, my Cayin A88T came with used 6550's. I like having spares, got some b'day $, bought some new KT88's. I loved the 6550's, I love the KT88's more. Convinced myself with my own expectation bias?

Source: Brent Jesse, http://www.audiotubes.com/

I found this 'state of the tube industry 2016'

https://theartofsound.net/forum/showthread.php?44432-State-of-the-Vacuum-Tube-Industry-2016

is there an updated version somewhere?

re-reading your initial post, it seems like you, after reading, are concerned about ’probable failure’, and don’t want to ’wait and see’.

I get that, I always want a spare set handy, and I understand staying with KT88’s, seems wise.

So, what ’non-exotic’ RELIABLE KT88’s? It’s a simple question really.

I went JJ KT88 Blue Glass. Blue glass is just a different colored glass, just for looks, (mine are very visible), identical to their regular KT88. I’ve never had issues with JJ. My Electro harmonix 6550eh’s now my spares, maybe I’ll need them, after say 5,000 hrs playing time, for me 15 hrs/week that’s 6-1/2 years. Professional use in a guitar amp is a whole different thing.

But, like anyone, anywhere, you can find ..., i.e. from ghosthouse, a member here posted in 2007 had nothing but trouble with JJ

https://forum.audiogon.com/discussions/expected-hours-for-jj-tesla-kt88

I did buy some Gold Lion Cryo Tubes once. Loose with birthday money, the difference is only .... WTH. I wouldn’t do that again. They are in an amp or the mono amps downstairs, I forget.

https://www.worthpoint.com/worthopedia/gold-lion-kt88-cryo-treated-matched-24909629