Conrad Johnson PV-14 background noise


I noticed a faint background hum caused by my CJ PV-14 (because there is no noise when I turn on the power amp only), it is not obvious but you can hear it when you get really close to the speakers. I have tried a set of new tubes but the noise did not change. Anybody has experience to share?

Thank you!
Have you replaced the electrolytic capacitors. That is the first thing I do after buying older equipment.
Rrog, it's a very feint hiss.

Orpheus, I have not replaced any of the capacitor. Do you suggest I do so? or it only applicable to PV12, no need for PV14?