Not sure if I committed audiophile social forum taboo by reviving a dead thread for a non-audiophile headphone. Here is my quick 2 cents on the Sony MDR-ZX310.
I was in shopping around in Japan for some cheap closed or semi-closed cans to be used in my car's rear seat entertainment units. Didn't want to spend too much since - being the family's driver-in-chief - I probably would never use them. After comparing various Sonys, Panasonics, Audio Technica and low end Sennheisers, I ended up buying 2 pairs of the Sony MDR-ZX310. The price was 2,350 Yen ( 20 USD) per can.
I did not give the headphones a "audiophile grade" audition at the store given the evening shoppers' crowd and loud background noise. But, the Sony's did appear to be the least harsh sounding for Japanese brands selling for around the same price. The Sennheiser was 3 times the price, starting around 7,000 Yen, thus I didn't bother to compare it with the Sony.
After getting back to my hotel room and plugged in the Sony into my MacAir, I was impressed.
To be fair, the Sony is not any where near audiophile grade or hi-fi grade. So don't bother trying to plug it into a headphone amp or expect miracles. You can't bend the laws of physics and economics with 20 bucks. Nonetheless, I actually enjoyed listening it as a casual pair of headphones.
Listened to some piano tracks and the Sony was not harsh. The sound is somewhat skewed towards the low end, with trebles muted. Treble lovers might not enjoy this can. But, IMO, most cheap phones are plagued with harsh grainy treble and thin vocals. It is quite nice that the Sony did not suffer these detriments.
Overall, I was decently surprised that I got this level of audio quality from phones at this price. It handles itself nicely and doesn't get in the way of the music.
Verdict: If your music taste includes instrumentals, vocals, mellow jazz, and 20 USD is all you got to spend on phones, give the Sony MDR-ZX310 a try. You might just stumble on something wonderful.
Pros: Cheap, decent balanced sound for the price, easy to drive, foldable, non-fatiguing sound, comfortable
Cons: Construction is a bit filmsy, lacks dynamic range, mid to low range sound gets boomy sometimes, treble lacks details
Source: Apple ACC 256kps quality - iTunes MacBook Air
Music auditioned:
Michael Nyman, Film Music 1980 - 2001 (piano tracks)
Amber Rubarth, Sessions from the 17th Ward
Howie Day, "Collide" (single track)
The Piano Guys, The Piano Guys
Fall out Boy, "Beat it" (single track)