Not sure which Amperex you tried, but I found the early 60's 6922/7308 to be the best in my system. Far superior to the later ones.
Preamp 6922 tube help
So my favorite tubes out of all the ones I've tried are early 1960 Siemens CCA, i find them to have an exteremely clean sound, fuller flat, tight bass, great imaging, just everything you would want. But because my system is on the neutral, the CCA has tipped it to the brighter side because of the "sparkle". I was wondering if anyone had another recommendation for tubes that perform like the Siemens, with its sense of realism but without the brightness in my system.
Here are the tubes I've tried
Telefunken E88CC ULM - clean tubes but the bass is too rounded out.
Mullard E188CC - too warm, way too warm
Voskhod Singlewire - great tubes but just didn't feel like didn't have any characteristics
Reflektor Single Wire - seems like the mids were a bit warm, but very nice tubes, but i would always rotate them out after a period because they didn't feel too accurate, but very sweet.
Amperex - Forgot which ones but the highs and lows were rolled off.
Electro Harmonix 6922 - has a basic tube sound to them on the warm side of things.
Here are the tubes I've tried
Telefunken E88CC ULM - clean tubes but the bass is too rounded out.
Mullard E188CC - too warm, way too warm
Voskhod Singlewire - great tubes but just didn't feel like didn't have any characteristics
Reflektor Single Wire - seems like the mids were a bit warm, but very nice tubes, but i would always rotate them out after a period because they didn't feel too accurate, but very sweet.
Amperex - Forgot which ones but the highs and lows were rolled off.
Electro Harmonix 6922 - has a basic tube sound to them on the warm side of things.