I've had a collection of NOS preamp tubes for some time and they refuse to die - Mullard 12AT7s, JAN Philips 12AX7, RCA 12AX7 etc. They're not all the best sounding - I find a modern preamp tube every once in a while that sounds fantastic...for about 3 months. But overall, given how little I paid for them back in the day, I feel they are / were worth it and for things like phase inverter or reverb position, you have a tube that will last for many years. Unfortunately, now you'll have to pay way too much for a NOS JAN Philips 12AX7. But, I just bought some ANOS power tubes, Tung Sol 5881 to be specific (test like new). Wow! These really sound fantastic. I've never had a power tube sound like this. And given that I got lucky and picked them up for about the price of new production tubes, it seemed like a reasonable test. Anyone else's experience mirror this? Any experience with older power tubes?