Last week, on a Facebook group page dedicated to headphones someone posted a query about which pair of premium headphones the group would recommend they purchase. The responses were as expected, with partisans of one or another of the models listed singing their praises and indicating that they would be the best choice.
Notice that I did not say, "Listen to each one for fifteen minutes..." Most likely the prospective owner will be listening during their "try-on time" so in some way considering the sound is a given. But if two headphones have the same approximate level of sound quality, any sane audiophile is going to choose the one that is more comfortable at the end of the listening session. It's important to wait at least a full fifteen minutes of on-head time. Why? Because some headphones that feel OK when you first put them on your head (or into your ear canals if they are in-ears) can become oppressive by the end of fifteen minutes. You need to know this before you make the mistake of buying them.
Over the course of the last five years I've reviewed a wide variety of earphones, some priced under $20 and some approaching five figures when you add in the headphone amplifier. While I'm sure I would be thoroughly chastised by commenters if I claimed there are under $100 headphones that are "better" than $1000 ones, but I have experienced $300 headphones that I preferred using to several multi-thousand dollar ones I've reviewed. And yes, in every case it was the fit that made the less expensive headphones a better option for me.
Head sizes and shapes are as variable and idiosyncratic as feet, and as someone who appreciates finely-made footwear, I am quite familiar with what a good fit feels like as well as what one that is not quite right can do to you during the course of a day. Just as one company's 9 1/2 B sized shoe is not necessarily the same size as another company's 9 ½ B, a headphone that "fits most heads perfectly" could very well not fit your head optimally. With shoes whether the fit is right can be pretty obvious, sometimes with headphones it takes a bit longer. All the on-line and mail-order shoe outlets have liberal "return if not satisfied" policies, headphone sales sites need to be equally liberal.
Trying before buying means is much easier if you have a local retailer who carries what you are interested in purchasing. In some places, like Denver, that's easily done - a trip to Listen Up, followed by a trip to Crescendo Audio will give a headphone fancier a chance to try the vast majority of premium brands. If you live in a less well retail-endowed part of the country there are mail-order headphone specialists such as Moon Audio who realize that items could be returned because the fit isn't optimal.
Let me clarify one last thing before we part company - I am not saying that sound quality does not matter, it certainly does; but that in the long run how a pair of headphones or earphones fit is going to have a greater bearing on how much you use and enjoy them than their sound quality alone, no matter how stellar that sound quality may be.