Just curious how long I should get out of the ECC88 tubes in my cdp. I'm not game enough to open the cdp up while it's under warranty to check the tubes.
An EAT ECC88 is rated for 10,000 hours, that's 3.5 years at eight hours a day.
If your tubes are old, and if you can see your tubes, look to see if there are visible signs of shadows or staining where the material from the cathode gets literally boiled off in use. This is what degrades the performance of the tube. If you can't see that, your tubes are probably OK.