Let me ask your thoughts on this aspect of it. As a brass player, and to a lesser extent perhaps on piano, the process of developing tone is by feedback. The first requirement is the internal concept - the imagination you speak of. This is normally developed by listening to performers you admire. Eventually you personalize it to yourself.
I absolutely agree with what you say here. I never meant to imply that I won't listen to live or recorded performers. That is a very important part of it. What I really meant is that after listening to a wide range of artists I actually prefer to listen to a MIDI file of the piece during or right before a practice session. The reason I do this is because I don't want to be tainted or influenced by the style of any one particular performer.
On the violin I make an exception to this rule when I listen to Hilary Hahn. If I were to somehow accidentally sound just like her that would be perfectly alright with me.

The second problem is learning to hear yourself. This sounds easy but it is not. Beginners are unable to hear gross mistakes in pitch or rhythm; even advanced players have to learn to hear their own tone, though they can recognize fine distinctions in others or on recordings. I suspect a protective brain mechanism at work. Otherwise we'd give up in disgust at our early efforts.
Well, I don't know about that. I can pretty much hear that I'm not good.

I mean, I do recording myself and listen to my own recordings. But I'm not surprised by what I hear. To me it sounds pretty much the same as it did while I was playing it live. And it's never very good. I think I'm a bit of a perfectionist and that can be a real pain sometimes because it often makes me want to throw my hands up and quit because I know that I'll never be able to make the music I have in my imagination. But fortunately I keep plugging along. I do make significant strides from disgustingly terrible playing to playing that I sometimes think, "Hmmm? That only needs to be refined"
Then the third problem is making the adjustment to move your real tone closer and closer to your desired mental concept - an effort that may take a lifetime.
Well, that's the problem. Does the refinement process ever end? I think if the musician is a true artist it never ends. Can you ever say that you've really played a piece that sounds precisely what you had in mind before you set out to play it? Usually we just settle for a feeling that it's probably about the best we're going to do with our current instruments etc. And the fact that we are mere imperfect creatures. In fact, when you get to a point where you feel that the quality of your instrument is holding you back that's a good place to be really. I think I'm there on the violin (because I have a pretty inexpensive violin). I would love to have a new piano too, but I can't really say I'm at a point where I'm seriously out-playing the capacity of the instrument yet (and I have a really crappy antique upright piano that I restored and tuned myself).
There is an inherent difficulty. For me, the stronger my mental concept, the harder it is to hear my output realistically, and vice versa. With your strength of imagination, do you have the same problem?
I don't think it's a problem. I can allow myself to imagine that I'm playing better than I am. I actually do that sometimes just for the satisfaction of it. I think those are the times that If I actually recorded myself and played it back I'd hear a huge difference because I was in fact fantasying in my mind that I was playing a lot better than I really was. I think that's good to do sometimes just for pure enjoyment.
But I also have the serious ability to "observe myself" almost like a unbiased second person. And when I listen to myself playing that way I hear all the mistakes that show up on the recording.
So I think I'm able to consciously chose which mental world I like to perceive. I think that when practicing its best to observe myself from the second-person perspective (where I can hear all the terrible things). But I think when it actually comes time to perform, I'm better off letting my imagination take over. The final result won't actually be as good as it sounds to me, but at least I won't have heard all the terrible things that the audience hears.

I think the real key is to be able to consciously choose your mental perspective. If your playing sounds better to you when you're actually playing it than it does when you here yourself on a recording then you are locked into a fantasy-reality. If you can get to a point where you can hear a recording of yourself and honestly (honest with yourself) say that it doesn't sound any different from what you heard when you actually played it, then you're able to face reality head-on.
Actually I think a person seriously needs to be able to hear all their mistakes live. If they genuinely can't here them when they are producing them it's going to be very difficult to deal with them properly.
I'm sure everyone has the ability to consciously choose between these perspectives. The question is whether they've actually even tried or practiced viewing their own existence from these two different perspectives. Many people honestly don't want to see or know about their own flaws. These two vantage points in life go far beyond playing musical instruments. How often to people really stop and think about how other people are perceiving their actions in anything they do? They can actually pretty much see that if they just step outside of themselves and view themselves from that (unbiased) second-person perspective. It can be hard to do for some people because they aren't willing to accept what they might see.
Well, that turned into a ramble for sure.
