I recently got 3 sets of headphones, find myself using all three for different purposes. The reviews at DIY audio, at Inner Fidelity and at this site were my guide. I'm a musical omnivore, like many here, listen to any number of different genres of music, including bass heavy dance/techno. This track, Material [Bill Laswell's project] with William S. Burroughs, has some deep bass without overtones:
That's my go-to track for bass performance. A lot of headphones boost bass around 100hz, that's the peak, what's going on below often doesn't have the impact. Sennheiser headphones tend to have that built-in EQ. I've got three with that sort of eq, the Urbanite XL, the HD 579 and the HD 599. I don't recommend any of these three, they don't improve much with eq. I know there's more to bass than the second harmonic of the electric bass guitar. Often, when we hear a bass, it's the overtone we hear. The 40hz part of the tone is more felt than heard, and has much more impact over loudspeakers in a big room than is possible with headphones. The "Soul Killer" track is one of the few tracks that one
feels the bass more than hears the bass via headphones. The track has bass at high amplitude going as far down as 10hz.
I used to have the Sony MDR V-6 headphones. They emphasize mid-bass over deep bass. Then I got AKG K167 headphones, with a lot more going on in the bottom octave. Those started to physically disintegrate. Too much hard [but not durable] plastic in the design. I had a little extra cash and as I listen to music over headphones more than over speakers, decided to get something better. The first set of headphones I got are the Drop 6XX headphones. They have the same kind of bass response as the Sonys I owned and the Sennheisers I still have, but fortunately they take to eq-ing. Of the three sets of headphones I got recently, they have the best deep bass response, but only when they are eq-ed. Otherwise, not so good. Also, they need a little extra power to reproduce that bass. So they are no good on my low-power DAP, the Fiio M3K.
Next up are the Philips Fidelio X2 HR phones. Tyll and Solderdude have nicer things to say about them than Arim. They are a little weird. Massive earpads, very open to outside sounds, image better than any other headphones I own. Some low-level distortion/blurring on everything. They don't go as deep as the eq-ed Drop 'phones, but they don't require much power either. Good for long walks as long as I can stay away from traffic. Not the ultimate in deep bass, but solid down to about 40 hz. Really great with small/medium sized combos in Jazz.
Of the three sets of headphones, the AKG K371 goes the deepest into the bass without eq. It is also the most efficient, requiring the least power. Very little distortion. In practical terms, these turned out to be the best for deep bass, though the eq-ed Drop headphones have a touch more clarity at the frequency extremes. However, the AKG K371 have the best bass overall in most circumstances. Not requiring eq or much power is very much in their favor. I suspect for folks DJ-ing, the ability to fold one earpiece off to the side of the head is very helpful, not to mention their ability to play loud with lots of bass and little distortion. Being the least expensive of the three is also in their favor.