The only small signal tubes I closely match are ones used as long-tailed phase invertors. Most amps don't have any provision to adjust the AC balance of the driver stage. For that I use a VTV small signal tube tester. It also lets you listen to the tube so you can check for noise and microphonics. Very helpful if you need to screen alot of tubes.
Do small preamp tubes 12ax7 need to be matched?
I had a Telefunken 12ax7 tube go out on me in the V4 (R) position of my Aesthetix Rhea, so I replaced the pair with stock Sovtek 12ax7WBs. Do I need to replace the Teles with a matched pair, or can I just pick up a single and throw it in. Obviously, I'll stick with smooth plate, as that is what was in there.