I believe these "micophonics" occur as tubes break down. It is a gradual process as I was told back in the late sixties when tubes were very prevalent in hi-fi amps and tuners. I have never heard of this in solid state devices,; could be . Perhaps James could explain this issue more accurately . 
Everything and anything in the audio chain is suseptible to microphonics. No exceptions. Why do you think people use giant blocks of dead tree under their gear and every isolation device ever made is used to reduce vibration aka microphonics.
This false idea that solid state is somehow 'better' than tubes is usually based on impressions that tubes 'color' sound where solid state doesn't. Nothing can be further from the truth. Solid state colors sound, tubes color sound, digital colors sound. It's the nature of the beast. Solid state has it's own set of problems that many find unappealing.
All that said I think this topic needs to encompass things like negative feedback, global feedback, rectification type, amp layout and class etc etc etc. Saying 'I don't like Solid State, I like tubes!' is missing the reality that both 'camps' have hundreds of different varieties within them. Tubes have SET, OTL, PushPull, UL, etc etc. Have those of you who profess to like only Solid State or only Tube listened to every variety available? I haven't and I doubt you have!