What exactly is critical listening? Who does it?

the concept of doing ’critical listening’ is simply listening with some sort of specific discovery in mind. as opposed to listening just to listen and enjoy the music, enjoy the musical journey, and having your mind free of the need to discover something. this to me brings the highest level of musical experience from my system.

some of this comes down to semantics. if you are comparing performances, or maybe drum solos, or vocalists, in some ways that is critical listening. OTOH my viewpoint is that is more non critical listening in an audiophile sense.

OTOH if you are listening for some aspect of the sound, or how gear performs, or how the room sounds, those type objectives push it to critical listening. and this type listening can become fatiguing and is less pleasurable. not to say that i don’t still enjoy intense critical listening. it can be fun especially if i get a question answered about something significant. so it’s useful to know how to do that too. 

while listening our minds are going to wander and all sorts of musical or sonic things might come to mind. but my viewpoint is that if we start our session without an agenda, and just let the music happen, that is non critical listening and the place i want to be most of the time. and non critical listening ends up revealing the most truth about my system since my mind is the most open to what the music is really doing.

I thankfully don't engage in audiophile nonsense such as "critical" listening. that is such BS it is funny. As if we were in the studio when the recording was taking place. the self fellation that occurs in these circles is comical

Suppose I want to compare the sound of the same radio program via streamer/DAC vs. broadcast (FM tuner). I simply switch between input X and input Y on the preamp. That's an example of critical listening, and it's neither nonsense nor self-flattery. Or I want to compare the sound of preamp A vs. preamp B into the same amp (one on balanced, the other on RCA). Just switch between the two inputs by pushing button on front panel of amp. That's another example of critical listening, and a useful one. The list of potential listening tests is pretty much limitless, but of course, once satisfied, we lean back and enjoy until some other aspect of the system warrants our critical attention.

To me critical listening is focusing on things like sound staging, pinpoint image location, and all the other esoteric things that a typical audiophile cares about.  Casual listening is not focusing on that but more so just enjoying the music.

If you are focused solely on listening you are listening critically. The more distraction the less critical the listening.