Wow, I own a DS2 preamp, a Levinson 27.5 amp, and I own Schiit headphone amps, one has Siemens tubes, the other a E-6SN7, with good Focal headphones these cheap Schiit amps are pretty formidable in sound quality. The E-6SN7 tubed amp is the best, but these are not NOS. The Siemens amp is collecting dust, and the tube was before I bought the amp. I have a lot of old tubes, 12A?7s, 6DJ8s, 6SN7s, and more collecting dust. I have probably listened to all of them for at least a short time, so I can't sell them as NOS, other than a few Chinese 6SN7 and Russian KT88, and various 300Bs, so I must be the worst of the worst, listening to alleged NOS tubes, and making them slightly used just to determine how they sound, and them sitting on them. I also have a home made KT88 amp I haven't even plugged in...