I'm a first year electrical engineering student and I had a lecture on Analogue and power electronics today. The main topic the lecturer was talking about was headphones and stereo systems etc. We learned about frequency responses and looked at product specifications and circuit analysis and he concluded that there is NO difference in quality between expensive or cheap products. For example £10 headphones as opposed to £300 Bose ones or beats or something. He said that our biases are due to placebo effects/ listening to one device at a higher volume makes you think it sounds better and so in shops they turn the more expensive devices up higher. Is this really true, or did I misunderstand something? Or is he just talking about in theory because even though I've seen the analysis, I'm finding it hard to believe all products are created equal. Hopefully someone can clear this up for me.