AND, a 30 year old RCA 12AX7 driving the gain in the preamp :-)
only bummer is: it's the only one i have.... when it goes out, it's back to new manufactured tubes :-(
Not so.
There are LOTS of NOS (New Old Stock) tubes out there to be had, in their original boxes, even.
The 12AX7 was/is fairly common. I'll bet I could find a replacement NOS RCA variant that shipped the same year as yours without too much trouble. In fact, I have one sitting in front of me right now, sans box.