How do you train your ears?

I have found it very helpful to listen to what other knowledgeable people say. People who have been in the hobby for a number of years. Have them go out to listen to systems with you either at dealers or other friends. You don't have to agree with them but often they bring up important issues that may not have occurred to you.

An analogy to this would learning about wine. You go wine tasting and have the wine server give you his take on the flavors in the wine.

Just a comment about commcat's post. I have no doubt that the tapes you and the engineer heard at your home sounded like the live performance. However, I once did an amateur stereo recording of a community-produced musical in an auditorium. I was a kid, it was 1977 - and used my Superscope Dolby cassette deck and a pair of $15 RatShack mics set up on a table about 10 feet back from the stage. Everyone who heard my unedited cassette recording was astounded at how much like the original it sounded, in spite of the obvious lack of fidelity of the recording chain and playback gear (my old stereo was OK, but mid-fi - Advent New Large, Kenwood receiver and the afformentioned Superscope deck).

Why? My theory is that all who heard the recording were present at the performance (or in it), and had some memory of the acoustic environment. Since my amateur setup captured the echos of that auditorium, the recording sounded like the live event. This effect was especially true when using headphones (I had Sennheisser 424X cans) fed from the cassette deck's headphone jack. Just my $0.02.

Listening skills are IMHO developed when you have a 'reference' and a 'goal'. If you don't know what is possible you don't have a reference. If you don't have a goal you don't know exactly what to listen for.

I agree with T Bone (mostly), you don't go to a live event for anything but to enjoy the music. While what you hear there could be a 'reference' it could never be a 'goal' because you could never replicate it at home (or even come remotely close).

Although I must admit the other night I heard a professional guitarist audition 3 new guitars against her own in a recital hall. The differences were clear for any one to hear but with her developed listening skills she could articulate the subtle differences in a more meaningful way when talking to the guitar maker. I could hear them, and they made sense when she discussed them, but I could never have described them so well. But now, if I were in the market for a new guitar (not an audio replication of one) I would now have a better 'reference', be able to create a realistic 'goal', and end up with a guitar I could be happy with.

In another, but relevant aspect, earlier that night she was conducting a master class with some college classical guitar students. She was talking about their technique in creating different complex tones. It was Greek to us, and the students as well, until she broke her comments down into playing just a few short notes using the technique, then it rang clear as a bell. You couldn't miss it!

I think many folks approach listening to an audio system's performance from the same prospective that they listen to music, they are 'seeing the forest'. When listening for system evaluation you have to be able to walk into the forest and examine each tree and learn to distinguish the difference between the Doug firs and yellow pines. It is there to hear but you have to learn how to focus on particular aspects and ignore others. Sonically there is an awful lot going on at the same time........

For example, how could you ever fully appreciate when you have achieved good soundstaging without ever having heard what is really possible.

You must get out and hear other well set up systems. Once you hear that 'great system' you have your aural reference, now all you need is a couple of great sources and some specific goals, and a lot of patience. It also helps when you can get other experienced ears to help you through this process.

FWIW.

Could you tell who she was?
What makers of guitar she has?
I play the classical guitar and own two luthier made guitars, so I wonder.

The guitarist was Sharon Isbin. She said the name of her guitar, I didn't get a clear understanding of the name, but it started with 'H' and might have been Holzgruber. I did a search and its tonal description matched my recall. There is a picture of her on the CAMI site with (I believe from visual recall) this guitar - perhaps you can pin down its identity. It was acquired (if not made) in 2007 and has a cedar board, rosewood sides and back which was either unstained rosewood or had inlay. I suspect the former but that is just AWAG, I saw it from 20 ft away. A gorgeous piece of work! It has a very rich tone which she attributes to the 1st string.

IMHO, the pairing of her and her guitar was just OUTSTANDING!!!! I'm going to get some of her recordings, she has a faily large discography. Especially her Rodrigo which she played for us. :-)