Vibration - What are the Main Sources?

A current thread discussing the best tweaks gave consistently high ranking for component isolation. I am curious to know where all the vibration is coming from that we are addressing with isolation. I understand that high volume listening can create significant vibration, but for the sake of this discussion let's assume we are listening at moderate levels. Can the vibrations from moderate sound levels affect the quality of sound? Are there other common significant sources of vibration that we are guarding against that can dramatically affect sound?
I will open the door to shameless promotion. I have limited vertical space in my rack, any suggestions for low profile feet/dampers that are actually effective?

It would be helpful to know what are the components in your system to suggest effective isolation / tuning. Your goal should be to seek out devices that do not offer a flavor or house sound. Isolation is all about less being more. Basically, products that have no effect on what should be in a musical presentation by eliminating more of the things that should not be. 
It would be helpful to know what are the components in your system to suggest effective isolation / tuning.
 Primary components are Schiit Gungnir, Schiit Freya +, Coda #8. Primarily looking at more isolation for the Schiit components for starters.

For isolation from EM fields Start with physical distance between components. Especially keep preamps and source devices well away from power amps and powerful amps from each other. Also from any nearby appliances with transformers as well if possible.
Low level phono amps are most sensitive. For example I placed my step up transformer in a mu metal foil tube to shield it from noise induced by nearby electrical devices.

Avoid running power wires parallel to each other and ICs if possible.
For physical isolation isolate speakers from floors if needed as in case of suspended plywood floors. If things in the room vibrate when you jump up and down speaker interaction with the floor is a likely issue.
Turntables are a whole other story when it comes to physical isolation.
If you address these things in most cases should be on very good shape. If gear rests on any solid foundation to start additional physical isolation will likely not add much if anything.
I've used inner tubes on heavy bass bins on concrete. It really effected the way the TT worked.. Radio stations by the freeway trick.

Over air the tube get craft foam blocks put them in the corners under the subs box. THEN let some air out until it just rest on the craft blocks.

I isolate, multi springs in holders and some type of soft silicone platforms. Adding weight works. Wrapping a quiet brick vs a noisy one help too. 

For "Rack mount" spring load between components, that works very nice. It adds load but not to much weight..

There are some VERY effective low cost solution to vibration control, how they do look vs how they should look is a different story.. 

There is some easy effective more expensive alternatives to.
Great looking, easy to install, easy to adjust and very effective is appealing.