After reading about people liking the Tungsram PCC88 in their pre-amps, I thought I would give it a try. I put them in the BHK amp a while back and quite liked them.
As for the preamp, I installed them last night after moving the two voltage jumper thingies over one spot (i.e., over the first two of the three little metal prongs instead of the last two). After turning everything on, I noticed that there is quite a bit of hiss / noise coming out of both speakers now (hiss in the tweeter; a low roaring type noise in the woofer - Dynaudio C1s). Not noticeable a couple of feet way but standing beside the speaker, you can hear it. Once music is played, it sounds great, but presumably the hiss is still there negatively impacting the music.
With the original tubes, virtually no noise of any type was coming from the speakers. Turn off the preamp and the speakers are dead silent.
The tubes seem to be installed correctly and are in tight.
Is this likely a case of getting a bad set of tubes? Bought them from a dealer (same one that I got the tubes that went in the amp) and so they are supposed to be new.