when a person plays they *always* put some feeling into there music.
How do you know? I don't believe that at all. It's completely possible to move your fingers and get a piece note-perfect with your mind elsewhere. That's not expression, that's playing on autopilot. I also believe that it's possible to play a piece of music, concentrating
on the music, but not be expressing anything other than what's written on the page in front of you, especially if it's a composer or piece you don't really care for.
I have never once come away from a performance feeling as though a musician has bared his/her "soul" to me, or that I know any more about them than I did before I heard them play. I
have come out of performance where the performer has been visibly moved by the music -- and he may have
thought he was baring his soul, or intended for that to be the case -- but that didn't affect my
own perception of it. If it's a moving piece, then if it's played well I might be moved by it -- the performer is just a means to an end, a communicator between the composer's intentions and an audience. Some do it better than others, some have a particular affinity for specific composers etc., but how often do you read a review of a performance where the critic waxes lyrical about how wonderfully you can feel the
performer's anguish, or happiness, or misery?
it might not be expressed in their playing though.
If it's not expressed in their playing then presumably you mean their face and movements? That can easily be nothing more than theatrics. (I'm not saying that's always the case, just that it's easily done. Actors do it for a living.) Some instrumentalists barely move when they play. Some play instruments where facial expressions aren't very practicable. Is, say, a pianist who weaves around at the piano, rolling his/her eyes around and making weird faces "expressing his heart and soul" more than someone who's fairly still when they play? I find it a bit distracting when the performer "gets in the way" of the music like that.
This may be a very cynical thing to say, but I think that "showing your heart and soul" is nothing more than a quixotic figure of speech people use to gush over an excellent performance (whether it's a visible performance or just a recorded one). It has no
real meaning. A musician can be moved by what they are playing, and this may or may not have an effect on the listener. But I think that, for example, when Gould called Richter "the most powerful musical communicator of our time," he didn't mean that it was
Richter's own heart and soul he was communicating.
I'm sure others will disagree, which is fair enough. I rambled a bit there.

Jas