People are social and it is normal to have concern about what other people think of us. Afterall, we cannot succeed materially or emotionally without the feedback/appraisal of those around us. To say we do not care what other people think of us is really just a statement of denial.
As for the stereo system, I am happy to play something for someone if they show in interest in my system. I have no feelings about it one way or the other. Many people seem to barely notice my system and I don't bother to play it unless they ask and it happens to be on. On the other hand, on the rare occasions that I get to have a fellow audio hobbyist over to hear my system, I actually feel a little nervous. I guess because I know I am going to get a valid critique from someone with knowledge and ability to evaluate my system. I appreciate honest criticism because it is easy to get complacent or used to a certain characteristic and their fresh viewpoint can give us a direction to go for further improvement- if I feel like it is worth it, of course.