It's easier to tell the differences when your running the amp loud and hard. If you're not pushing the amp, you won't hear much, if any, difference.The dynamics of such a story are unknown to me but I'm glad you're a happy camper.
I guess with more ear training I'll get there
The supply of the more common types of (NOS) tubes for guitar or bass amps, are drying up. Current prices reflect that. In general, your NOS preamp tubes in a circuit will probably last more than you, or me. I say, use them now or sell them now. Those NOS RCA's are a $100 to $175 these days!
10 years ago, the price was less than half of what it is now. At the time, I didn't mind spending a few extra dollars on NOS preamp tubes. Nowdays, it doesn't seem to be worth it. Unless an insane deal comes up, I think I got my corksniffing with NOS tubes under control.
The amp is so well dialed in. It's been my main guinea pig for mods for the last 12 years. On the outside, it looks pretty stealthy. Inside, it's a different story.
It's a 1982 JCM800 50watt 2x12 Combo (Model 4104). I've had this amp since 1986.
