12AU7 Genalex or Psvane for Cayin Hybrid Integrated H80A

Why waste your $$$ on these new production tubes? Even the best won't last as long (or perform well for as long) as a halfway decent pair of NOS tubes. Call Andy at Vintage Tube Services. Tell him the sound you prefer and he can hook you up with a very nice pair of NOS 12au7s that will measure and perform better than any of these Chinese relabels, and for </~$100. Spend a few dollars more now and you may never have to buy another pair. 

Very curious how a true NOS tube will fair in my system, since I have never tried any NOS tube. Concerned mostly with noise that some report NOS tubes exhibit, but then again that concern may apply to just about any tube.

NOS are less noisy than the typical new-production tube. They’re also far more reliable. I have a pair of RCA 12au7s that were manufactured in the 50s, and a pair that were manufactured during WWII. Both perform better than the pairs of new-production tubes they replaced. Unlike many technologies, tube manufacture has not improved over the last few decades, quite the contrary in fact. Some of the Chinese factories have improved their QC in recent years, but the reliability and build quality of their tubes still pales in comparison.

On second thought, please stick to new production tubes. Stay far, far away from NOS tubes, you should want nothing to do with them. They’re absolutely terrible!