I just bought some JJ E88CC tubes and have used them only a few hours. On Sunday I listened to the CSP2 for about an hour and left the unit on several hours more. When I came back to it, the unit would not play out of the left channel and the right was curiously not right. After testing the tubes it turned out they were dead. I doubt I had 12 hours on them total.  I swapped the 6N1P's in the 3 positions and it worked fine.