Update: I am now the happy owner of a Hickok tube tester, and can provide trans-conductance (gm) test results for any tube on request. I find myself in need of funds for university books, so I must thin out the tube herd. All of these tubes perform excellently and were tested with my Sennheiser HD800 and the highly sought GEC A1834/CV2523 power tube on my Bottlehead Crack + Speedball. They were bought with test ratings near or above typical NOS, and matched sections. The 6SN7 are compatible with the Crack with the appropriate 8-to-9 pin adapter (I can recommend a good one). The E80CC are also compatible with the Crack+Speedball without an adapter. Both types have a distinct sound signature from 12AU7/ECC82 tubes. The tubes marked with an asterisk come with their original box. The rest will be shipped in a generic white box. I will send pictures on request. 12AU7/ECC82 RCA Cleartop (side getter, some rebranded Conn) - $15/20 *Amperex 12AU7/ECC82 (Made in West Germany, Siemens rebrand, Orange Globe version, code 9-50) - $25 Valvo ECC82 (Herleen, Holland, code Gf9 ΔXXX) - $25 Phillips ECC82 (Herleen, Holland, code Gf8 ΔXXX) - $30 *Tungsram ECC82 (Made in Hungary) - $30 6SN7, 5292 Sylvania 6SN7GT (Made in U.S.A., lightning bolt symbol, bottom getter) - $45 Raytheon 6SN7WGT - $50 E80CC Valvo E80CC (Red logo, gold pins) - $60 Either send me a PM with which tube(s) you'd like to purchase, or let me know what sound you're looking for and I'll make you some suggestions. I'm willing to offer a discount for multiple purchases.