This has been my problem for my whole musical life. I remember when I started playing flute I used to ask my brother if he thought I had improved. He listened to me practice every day for hours on end, so he had about as much objectivity as I had. All he could tell me was that he noticed when I changed the order of the things I practiced. My parents also had their subjective positions relative to their own musical and parental insecurities. When I asked Julius Baker, my teacher at Juilliard, if he thought I had any talent, he told me to see a psychiatrist. Being a dutiful student, I did. The psychiatrist and I talked mostly about my difficulties with my teacher not paying much attention to me at what usually turned out to be group lessons. I think that my psychiatrist believed, in his heart of objective hearts, that I was probably not worth paying attention to as a musician. He came to a recital I gave (which was really quite good), and then he totally changed the tone of the therapy, aiming for more Freudian ways of using my parents' insurance company's money.
So, now as an adult I am often in the position to validate the work of others. I do it as a reviewer, as a program annotator, as a teacher, as a parent, as a spouse, as a chamber music partner, and as a friend. I'm actually quite good at it because I have had to be self-sufficient for so much of my developing life. I have even sought out opportunities to do it, sometimes blurting things out when I am not even asked.
I also have to do it for myself. Most people know me as a person of rather strong opinions, and most people imagine that I don't need to have them validate the work that I do. Maybe I don't, but then again, like everyone else in the world, I have an "inner child" who wishes that every ball that I throw into the world will come back at me, that every review or article I write is a potential conversation, that every piece I write is something that people will enjoy playing and listening to.
Maybe there is no real self-sufficiency when it comes to music. So we just plug away, working in isolation, and hoping for some kind of connection with the outside world. We keep ourselves in the company of great musical minds, having most of our musical intimacy with people who are no longer alive, people who have been kind enough to leave something of their musical selves for us to play. And we keep looking for people who understand the importance of communicating honestly through music.