Shure SE530's under $250
The Shure SE530's are fantastic Touch ear canal phones (ech). The pioneering triple drivers (in an ech!!) really deliver near reference quality audio, especially when playing AAC Lossless files. Lower bit-rate recordings sound clear, but are compromised by the triple drivers (different instrument tracks often suddenly play from a single driver, or earpiece). Maybe the recordings are monaural, but I just don't know enough about digital music.
Obviously the passive sound isolation created by any two of the 16 or so different foam, rubber, and triple flange sealants is excellent, but don't expect to hear your name called. These phones redefine immersion. If you're really waylaid by the isolation, opt for the 530PTH's which, though I've not tried them, offer push-to-hear technology. Apparently, the listener pushes a button that turns on an external microphone when hearing external voices, or noises is critical. I've never read about the mic compromising the sound quality, but it seems possible.
Unfortunately my first pair "broke", or I did something unknowingly detrimental to them, and so I was worried about their durability. While not as durable as crappy phones, my second pair has worked excellent.
I bought mine from Headroom, at a significant markdown (they were around $250 in September), yet still received the 30 day exchange (or refund, had I chosen) service. They even sent my second pair the same day I called about the problem, and included a pre-paid Fed-Ex box for the return. Given their low prices, unbelievable web forum, telephone sales and tech support, and their handbuilt headphone amps, DAC's (to fit most budgets), and recabling services I'd buy no where else.
Meanwhile, the SE530's, when last I checked, were $500 at the Apple Store, with a three-week shipping delay. I doubt they offer such considerate return policies either.
Finally, it's worth alerting anyone considering higher-end phones, to check the headphone's resistance, for anything over 65 ohms impedance will not adequately run off portable player power. The Shure's, and most other ech's are low resistance, but the Apple Store used to sell, and may still sell the AKG 701's, a circumaural reference can that while near the 65 ohm "cutoff", sounds little better than the Apple in-ear buds when powered by a flash drive media player. They were offered at full price as well. Sadly, the site comments derogated these amazing cans, which need a headphone amp, and 200-300 hours of "warming up" prior to optimal sound delivery. I have a pair connected via mini toslink to a DAC/amp combo, and they are as plush, and as captivating as $8K pre-amp/amp/decoder/reference CD player/speaker systems.
Finally, the Shure530's look beautiful, and luxurious, as they have a lustrous, carbon-fiber type earpiece, that matches the Touch, and needs no adaptor, as most iPhone headphones require.
However, the 210's are probably around $100, so unless your music is Lossless encoded, and you need triple drivers, you can get quality audio for less than expected.
Only after upgrading will you hear every note, even in the high frequencies. Nor does hip-hop require a compromised sound, at distorting volumes, just to hear the low frequencies. Therefore, it is probably a reasonable inference that high-end phones are worn at lower volumes, preventing hearing loss.