Are audiophiles people of sound prejudice?

Yes. Certainly.
All one has to do is go to any high end event and listen to the myriad systems on display and the loyal followers, the know it alls, the disparagers, and the ones with the bemused looks on their faces. We all know what sounds good to us from the journeys we've taken and it can only be seen through the prejudices we have developed.

I really like your question and the way you framed it.

I agree, we listen with our ears and can only really know
that single certainty. We listen with others and to others
systems, but we listen with biased tastes. Like eating a
great meal, certain flavors are more endearing to our palet
than someone else's. We base our opinions on many things but
mostly inner ego, or what satisfies us. Is that prejudice or
just selfish behavior, or are they the same?

Yes, I think audiophiles are sound-prejudiced. Audiophiles pre-judge based on the expectations and preferences of what sound quality is, built up over time. It's human nature. Being an audiophile is about sound quality and audiophiles are very discerning of it. Because the equipment is very sensitive and does not guarantee success when putting a system together, our prejudices make it complicated to achieve the sound quality desired. Audiophile systems are by their nature, not plug and play. There is typically trial and error involved in the process of building a satisfying system. Sound prejudice has much to do with the entire process.

Nonoise, thank you for your kind words and thoughts.

Theo, Prejudice is typically something which is prejudged. Much like premeditation changes a killing to a murder. It also confers the idea of a lack of openness to what something may or could sound like or be like. A musician may have, and hopefully will have, a very good idea of what their instrument should sound like. Selfish behavior is based usually on what one perceives is best for that person, which may or may not be the case. The difficulty with separating them is that one's prejudices may be so centered around one's thoughts of what is best for one's self that they can be difficult to disentangle.

Not at all. When something sounds right eveyone with the hearing will agree. As for slight differences in preferances, sure, they exist.