Good question. I learn something new every day as I am relatively new to the world of audiophiles, so I may be changing my opinions more than I will in a few years. I believe that frequency response is the most important determinant of how a pair of headphones sounds. However, there are very fine nuances that I am just learning about and I won't have my own preferences fully understood until I experiment over 1000s of hours more. I experimented with EQ where I tuned the VCs and my HD800S to the exact same curve. They sounded amazingly similar. Too similar as to be boring. When I A/B tested the VCs, the EQed version sounded more balanced to me. But, I felt like I lost the ZMF sound. Then, I turned off all EQ and just played it with the stock pads and I preferred that sound over my EQed version.
So, what is my process for selecting a headphone in the first place? I read a lot and wait until I see something that intrigues me. I read reviews to see what experts say. I take what I've learned about what I like and try to triangulate to see if I will like it. Then, I find a way to hear something for myself. I either audition them in a store or I purchase something that I will sell if it doesn't work out and the cost is the cost of learning. My goal is to try everything so that I can figure out exactly what I like and how everything else related to that. So, have I changed how I select a headphone? I guess not. I use a somewhat systematic approach that leads me to a greater understanding of my own preferences and the frequency response curve is one of the key data points that helps me compare everything I hear to everything else.
