Noise from Rogue 66 preamp...

From a relative "tube newbie" - when I tap the volume knob, power switch, etc. on my Rogue 66 preamp I hear the results coming out of my speakers. I did expect some type of low hum if the source is turned off and the pre and amp are on - a little hum at the speaker but I didn't expect the tapping noise to transfer right the way through. When playing a source the tapping can still be heard if I tap hard enough.

Bought from a reputable dealer, my linestage tubes are Mullard CV-4003 (12au7)with about 125 hours on them. Are they going "microphonic" and failing??? I recently took out the 4 phono board tubes as I don't use vinyl so I thought why run them if they are not needed (Rogue advised this would not be a problem)

Any thoughts would be most appreciated.