noise thru tube pre??

Microphonic tubes. Nothing to really be concerned about.

Not a problem if your pre still sounds good. Microphonic tubes can actually sound very good, but it is system dependent.

Probably time to tube roll anyway since you just got your new pre. Experiment and have fun. You will be amazed at the difference tubes can make.

You did not mention the the tube manufacture and type you are using.

With the volume turned all the way down put your ear close to each speaker, do you hear a buzzing sound from either speaker or both...

I bought a new pair of New early 60s white label NOS Amperex PQ 7308 tubes a while back. After about 5 hours on the the tubes I noticed a buzzing sound in the right channel speaker, from my listening seat. I also noticed at a normal listening volume level, just a light tap on the top of the face plate of my Sonic Frontiers Line One preamp I could hear the tapping through the right speaker. Luckily I had bought the pair of tubes from a Tube Dealer and he sent me a new pair.

What tube damper are you using? I highly recommend the Herbie's HAL-O dampers. Below is a link.

http://herbiesaudiolab.home.att.net/

You've got a microphonic tube. Since you only have one tube, get a new one thats been tested by a dealer for microphonics. Microphonics can effect the sound put out by your pre-amp even if you are not tapping the case. Vibrations come from many sources, including airborne.

Use currect production low noise tubes until you know the sound you prefer. Visit Audio Asylum tube forum and do a search on the 12AT7 you are using for suggestions on good currect production tubes. I don't use any in a line stage so I have no recommendations.

Re above comment 'microphonics can actually sound very good' - I would add 'if you like distortion'. In fact the presence of microphonics can give you some of that upper mid/high end distortion (glare, grit, grain, etc) that most folks hate.

I thought tube gear was always noisy, is it more than usual? : )