Thanks for responding, mgalusha.
First, I am aware that "in my amp" and "to my ears" are two deciding factors and that I too really must acquire a small harem, for lack of a better term, of output tubes and listen for myself as to what
I like best. Also since the amp can run any type from 6L6 to KT88 I will need to try some variants too.
I do have some unjustified prejudice due to the previous owner telling me that within his period of ownership he had determined that the JJ KT88 was the best tube in the amp and they came with a very fresh octet. Having set them up in my system I was floored at the SQ. This was my first experience with an electronic piece of equipment having a transformational effect on my system. Prior to that only speakers had that dramatic of an effect and with speakers it's obviously intuitive why this is. Changing electronics had always had mostly subtle effects with the most dramatic being a change on overall voicing, i.e. darker or brighter, smoother or more etched, etc. When the VACs came into my system the effect was like someone removing blankets from my speakers this new level of clarity and transparency was jaw dropping! It's
still exciting after nine months, five speakers, speaker cable upgrades, and various other tweaks.
Here's link to my system at present. Lately I have noticed I'm having to pay more attention to the bias and figured I may as well start looking for tubes.
So I will give the Pentas go but will also slowly rotate some others through. I have rolled some various 6SN7s from my stash including NOS RCA, NOS Tung-Sol, and some early Sylvania chrome-domes which are the cat's meow and remain in the amps with backups acquired. The amps take a pair in each monoblock.
There's more in store.
BR,
JakeJ