This is like saying that the Tesla P100D is the best car, and any other car more expensive is silly because the Tesla has the best acceleration. Frequency respo

This is like saying that the Tesla P100D is the best car, and any other car more expensive is silly because the Tesla has the best acceleration. Frequency response is one aspect of sound, but it's not everything. Much about sound is subjective. I personally didnt't like the way Audeze LCD-2s sounded when I listened to a pair a coworker brought in, greatly preferring my Shure 1540s. There are, to be fair, plenty of headphones in the $150-$400 range which try to do something to the music (like add xxtreme bass) and end up not doing a very good job of it. Sony even made some, check out the MDR-XB500 and the super over-the-top MDR-XB1000 which apparently actually sounds pretty good. The Sonys you mentioned are great headphones and a super deal at $60. They are actually used in the pro world for stuff like location sound work and in studios. Another popular studio headphone which is a "a good deal" are Beyerdynamic DT770 Pros (~$175 street, you've probably seen them before). Giving either of these to someone who has no experience with nice headphones is a treat they won't forget if they're into music. I was lucky to get my first pair of nice headphones when I was about 14, some MDR-V700s. They hurt my head after about an hour of wearing them but they sounded way better than anything I had heard before (this was also in the 90s before headphones were a common hobby). It is for sure a game of diminishing returns beyond a few totally-great headphones which are actually used for making music. Other equipment also plays into this; the difference between a JDS Labs O2+ODAC and Chord Hugo + Cavalli Liquid Gold is there but probably not worth the price difference of a decent used car for most people. Go to a hi-fi store and listen to some setups with your own music. There are also headphone meets all over the place, and huge events for this stuff: http://www.canjamglobal.com http://www.canjamglobal.com and of course there is https://www.head-fi.org https://www.head-fi.org if you're interested in getting into this stuff.