Bloom air around instruments

The ambient sounds of the area the recording was recorded in.  By area ...indoor (Studio) vs indoor (concert hall/non-studio building) vs. outdoor area.    Some like to call this "air" which is fine, but it would seem that the "sound" of the recording area is most likely that "air". 

Add a filter choke to the preamp and amp and that will get you to understand how things begin to work and sound.

Happy Listening.

I've never heard audiophile "air" at the thousands of live acoustic (not amplified in any way) concerts. I think, in general, it's probably a pleasant artifact of recording and reproduction.

That’s where recordings are better than live acoustic performances on a good system. 

Lowering the noise floor by having clean power through the mains will reveal air and ambience on the recording. Also vibration control on components and rack, and an acoustically treated room will reveal air and more in the recordings.