About 6mos ago I purchased a pair of NOS, RCA Clear Top 12au7 for my Line Magnetic DAC. I purchased them from a shop that I knew was reputable. When they arrived and I opened the boxes I noted both tubes had a serious flash marks. I mean both looked identical in the way the flash was located in the tube. Called to ask why & was told that happens sometimes in testing and that the tubes in question tested as NOS. I was skeptical and had them tested locally. Sure enough as close to matched as if ever seen and both with NOS life expectancy. Both dead quiet and the tubes themselves brought out the very best in my setup and for certain, DAC. What can I tell you... always a roll of the dice when purchasing NOS so make sure you have a dealer you trust.
Driver Tubes 6922
I've heard a few people opining that the driver tube can be the most important tube.
Why is this?
What do you look for in a 6922?
What differences might I expect to hear replacing my modern GL e88cc with an expensive NOS 6922?
Any recommendations for a 6922 based on actual experience?
Thanks
TD