I think it's a great question. I think the best answer here, from my own experiences, is that yes indeed our subjective assessment of sound quality, especially with something we can't "blind" test like headphones, is highly affected by the appearance, feel and knowledge of the brand and price - at first - both in the short and long terms. In the short term we are impressed, or have our expectations confirmed, only to have that experience change with more listening to a specific model. Long term, with experience listening to many different things, we become better listeners and more quickly hear the things that took a long time to recognize when we first began. I'm really just repeating what others have said, but these two factors summarize what seems important to me from all of these replies: placebo effect is real but it fades, and the better you get at listening, the less you are affected by it in the first place.
So how much do you think the placebo effect impacts our listening preferences?
My hypothesis is that for ~%97 of us, the more a headphone costs the more we will enjoy the headphone.
My secondary hypothesis is that the more I told consumers a headset cost, the more they would enjoy the phones. i.e. a $30 headphone < $300 headphone < $3,000 headphones <<< $30,000 headphones.
I’m willing to bet that if I put the kph 30i drivers in the focal utopia’s chassis and told participants in this fake study that the phones cost $4k.... Everyone except for the 3%ers would never guess something was up. The remaining 97% would have no clue and report that it was the best set they ever heard.
Then if I gave them the kph30i and explained it was $30. 97% of people would crap on them after hearing the same driver in a different chassis.
My ultimate hypothesis is that build quality and price are the two most important factors in determining if people will enjoy a set of headphones. This how I rationalize the HD8XX getting crap on when only 3 people have heard it and publicly provided their opinion lol. "It’s a cheaper 800s, of course it’s going to sound worse!"