I purchased recently the camera X-S10. I noticed that silent humming sound today, if I put my ear on the camera. I am glad that the camera I received is not defect.
I was interested whether or not I can hear that sound while I record a video. For comparison, I recorded with the same lens a video using X-T20. X-T20 is absolutely quiet. The same background noise was to hear in both recordings. So, I concluded that the humming sound is not annoying.