Tubes and microphonics

I want to know when microphonics affect the sound.
I have a Sonic Frontiers Line 2SE Preamplifier. I tried many tubes like Valvo, Siemens, Reflector 6H23NEB.
Recently I bought two matched pair of Amperex 6922PQ White Label Made in USA. I think that the Amperex are better than the others, but I could see that they are less silent.
When I knock the cover of the preamplifier I can hear the knock clearly in the speakers. That not happen with the others tubes. The 6H23NEB are the most silents.
I think that Amperex have more gain than the others. But I donĀ“t know when that is critical to the sound.
Please let me know your experience with your tubes and preamplifiers.
Pablo - the 6922/E88CC family are very microphonic, as you probably know. You may want to try some tube dampers to help out with that. I've used Herbie's and Mapleshade and either works very well. Tubes in preamps are usually very sensitive to vibrations and will amplify them (as they are prone to) at the speakers. It's more of a surprise that you do not hear the knocking on the cover with other tubes, than it is that you would with the Amperex. Anyway, give the tube dampers a try if it is a problem. Herbies are inexpensive and effective.

Pablo, I own the SFL-2 and use Amperex PQ tubes and you'll find the best position for your best tubes are in LVS2 and V2 and LVS1 and V1 are the next best position. I have two sets of red labled Herleen Holand tubes that I tried and installed the first pair in LVS1 and V1 then the next pair into LVS2 and V2 positions and got noise when tapped on tubes as you described so I swithed the LVS1 & V1 pair with LVS2 & V2 pair and no more noise. I now use Amperex PQ in LVS1, V1, LVS2, V2 positions and the red lable Herleen Holand Amperexes in the remainig positions and all is quiet, also as mentioned above the Herbies tube dampers work great.
Can anybody tell me their opinion for the Amperex PQ orange label USA late 60's early 70's production?Need for the SF SFD 2MK2 Dac.
Elduende 14,sorry for highjacking your thread
Marco you should know any comments?