Why is it so easy to tell the difference between live and recorded music?


I would direct you to Steve Guttenberg’s most recent YouTube video. It is a question that I’ve often asked myself. Any thoughts?
marklindemann
If you mean live music that is amplified like rock music, then the live sound you hear may be from the PA system which gives it a very forward, often one dimensional sound. Also the reverberation may affect the sound (many greatful dead recordings suffer from this). When audiophiles say live music is the ideal I often disagree unless they are referring to classical or chamber or choir music. I enjoy rock and blues concerts but find that many concerts have pretty bad sound due to the location (eg basketball arenas) but also because everything is pipped through the pa loudspeakers which to me often loses the separation and texture. When I played in a band I loved hearing the drums and fender amp directly when we rehearsed. Going the the PA system usually degrades the sound unless great care is taken by the performers and crew. 
Back in the 1960s AR marketed their AR3a loudspeakers with a live vs. recording demonstration.  A string ensemble, solo violinist or guitarist would play a piece and at some point the sound would be switched to a recording.  Listeners would then be asked to comment whether they could tell when the switch took place.  The majority of listeners could not accurately detect the switch over.  A key element of the demonstration was the special way the recordings were made.  They were made either outdoors or in anechoic chamber to avoid the "double acoustic space signature" effect during playback.

I remember seeing pics of those live vs. recorded demonstrations onhwy61, in the 1960’s/early 70’s AR ads and sales literature. They were done in NYC, at Carnegie Hall, I believe.

By the way Bose 901 fans, the "double acoustic space signature" effect onhwy61 mentions is one of the things wrong with that speaker. The 89%/11% reflected-to-direct sound Amar Bose measured in music halls, and which the 901 mimics, ignores the fact that recordings of orchestras in those halls, Dr. Bose’s standard for recorded sound, already contains the hall’s reflections. The 901 then doubles the effect. For the 901 to work correctly, music would need to recorded, as onhwy61 said, either outdoors or in an anechoic chamber, free of reflected sound. And then there is the case of studio-recorded music, which bears no semblance to the direct vs. reflected sound of large halls and churches, making the speaker absolutely inappropriate for studio-made recordings. An extremely flawed speaker conception and design.

onhwy61, I've heard of similar demonstration (long time ago) with symphony orchestra and the best audio system available behind the curtain.  Herber Von Karajan, asked to participate, detected system with ease every time. When they asked him how different it sounded to him he said that record player was slowing down slightly during orchestra's forte.   Surprisingly famous musicians with such perfect hearing often don't care about the sound.
Not at all easy with large ATC to recognize the difference between live and a good recording. I think wide even dispersion and high dynamic range and a neutral uncolored sounding speaker are major factors but there is a lot that is required - so it is rare enough that I understand why many folks might think it would be impossible.

I have followed Steve for years and I think his technical knowledge is outstanding but his hearing preferences are towards colored hi-fi style sound. Nothing wrong with his tastes but you arent ever going to find realistic audio reproduction with those kind of preferences.