Most of the headphones I've tested over the years weren't designed to have a neutral balance of bass, midrange, and treble frequencies. Manufacturers are well aware that most people like bass, and that buyers tend to favor one headphone over another based on how much bass it produces. I think that's obvious, but a recent study cited in Brent Butterworth's blog countered that assumption. "The Relationship between Perception and Measurement of Headphone Sound Quality," a paper by Sean Olive and Todd Welti presented at last October's Audio Engineering Society convention found that a panel of trained listeners preferred the more accurate measuring headphones in a series of blind tests. The headphones tested were the V-Moda Crossfade LP ($199), AKG K550 ($299), AKG K701 ($299), Audeze LCD 2 ($999), and Beats Studio Limited Edition ($299). Olive and Welti didn't reveal the winner, but they found the panelists preferred the more accurate and better measuring models. I think Olive and Welti took a wrong turn by relying exclusively on "trained listeners," people who have an accuracy bias. The general public, and the youth market in particular, have very different biases. They've made their preferences known by buying millions of bass heavy headphones.
As a headphone reviewer I've auditioned hundreds of models, and I've noticed that, over the last two or three years, a very bass heavy sound is the new norm. I much prefer the sound of the Etymotic ER-4P, Audeo PFE 232, Logitech UE Reference Monitors, and Jerry Harvey JH-13 Freqphase, which are among the most accurate sounding in-ear headphones I've tested. The Noontec Zoro, PSB M4U 2, Hifiman HE 400, Beyerdynamic T90, Sennheiser HD 700, and Audeze LCD 2 and LCD 3 are among the most accurate full-size headphones I've tested.
They're not the most popular headphones, and I'd guess the combined sales of all of my favorites are a lot less than the sales of Beats by Dr. Dre Studio headphones. That's why I'm far from convinced that most folks will ever prefer accuracy, and judging by the sound of the current crop of headphones from a wide range of manufacturers I don't see them moving toward accuracy. I generally like Sennheiser headphones, but there isn't a consistent Sennheiser sound from one model to the next. That would be the case if each one was designed to be as accurate as possible for its price class. No, Sennheiser and other manufacturers strive to make headphones that sound great to potential buyers, and accuracy has nothing to do with it.
Please share your thoughts about your headphone's sound and why you like it in the Comments section.