Hi, I have a few old 12ax7 tubes that I've pulled from two donated scrap organs, and my ears honestly can't tell the difference when I test them each in my old 1957 Gibson GA9 amp (two 6v6s, and preamp is a single 12ax7). I have a Marshall 4210 combo that I could use four of these 12ax7s in for V1, V2, V3, and V5 (I have a 12au7 for the V4 reverb tube), but in my quick tests I can't really hear much of a difference in that amp either. I was hoping someone here could tell me, is there anything in this list that you'd definitely hold onto and use, or are they all unremarkable? Maybe I'll eventually appreciate it after playing with it at volume for an extended period. I'd like to just keep the four or five best tubes and put them in the 4210. Baldwin-branded Slyvania 12ax7 from early 60s Baldwin 12ax7 from Japan early 60s Wurlitzer-branded RCA 12ax7a short gray plate, early 60s Wurlitzer-branded GE 12ax7 long gray plate (USA), early 60s GE 12ax7 short gray plate (Canada) IMG_20200803_164923 by joebor1776 posted Aug 3, 2020 at 5:09 PM I know the obvious answer, if my ears can't tell the difference, it doesn't matter...just looking for a "here's what I'd keep" opinion. Thanks!