Tube Whine noise...Please Help


Hi everyone.

As a newbe to tubes I am having a problem that I need some help on. I just received my Musical Design SP-2 preamp and while it sounds wonderful, occationally there is a high frequency whine/whistling noise coming from one or both speakers. The SP-2 uses 2 6922 that the previous owners said were NOS RCA types. I want to know if the tubes went bad and needs replacing or if there is another problem that I need to look for. Thanks
speedracerucr
Thanks for the replies. So if it is indeed microphonics, what options do I have to eliminate it. The ringing is pretty annoying. Even when no music is playing and the tube preamp is left on, the ringing will occur sometimes. Am I correct to assume that I will have to switch out my tubes for ones that are not microphonic? Also will Herbe's Hal-O dampers help?
I have had good success with HAL-O's. I also have had good luck when buying new tubes getting the low noise "LN" variety. It may not eliminate it, but it could greatly reduce it. In my previous post, I left out the "in" in front of correct.

Thermionics are what makes the glass bottle work, to make the music go round-n-round
It should not be necessary to waste money on tube dampers as properly functioning tubes won't whine.
It seems to me that the surest thing I can do to eliminate the ringing/whining is to replace my tubes. Since this is the case, are there any low noise/low microphonic 6922/6DJ8 that you can recommend to me? As of now, I am probably not looking to tube roll with NOS. Thanks