There are two things you'll notice when listening though MDR1-A. First, you're going to be overwhelmed by the pounding bass, and second you'll be impressed by its soundstage. I feel that your enjoyment of these headphones will matter a lot on what kind of music you usually listen to. If you are a critical listener who enjoys their Stravinsky, Johnny Cash or Vivaldi, with a variety of instruments in the background, then you're going to be turned off by them almost instantly. However, if you are the kind of person who enjoys the ground-pounding thumps, trip-hop and a some proper rap, then these should definitely take a look at them.
Since these are a pair of cans that don’t need all that much amping, you could use your smartphone just as well as your DAC & AMP combo, or DAP.
Other than the powerful bass, Sony has equipped this headset with mellow mids, and a warm, sparkly treble, that never, ever becomes too sibilant. Overall, the listening experience doesn't cause any kind of fatigue even after, let's say, 6 hours of continuous playback.
MDR1-A features a powerful, booming and slightly sluggish bass. It's lagging behind V-Moda XS' but only by a little. Sub-bass is also very noticeable here, moreso than on the aforementioned V-Modas. It sound good with slow kicking songs like MS MR's Hurricane or Arctic Monkey's Do I wanna Know, but it can't keep up with fast drumming tracks like Brianstorm or even Dream Theater's Scarred.
Alas, such a powerful bass will most assuredly affect the mids, at least on the lower midrange, and as a result some instruments lose presence. Still, what's unnaffected remains pleasantly warm, full, and considerably more enjoyable than the bass.
The treble follows the mid-range trend, being mellow, lush, with a decent amount of sparkle and musicality. It's not really natural, but still quite enjoyable to listen to. Since the treble is not sibilant in any way, shape or form, you could stay with these headphones for an entire day, and have no listening fatigue whatsoever.
MDR1-A has one fantastic thing going for it. It's one of the most open sounding closed-back portable headphones I've listened to in recent memory (isn't that a mouthful). Sometimes I hear instruments coming from the back, the sides or from a different layer, and that's probably the most impressive thing Sony did with these cans. The soundstage is wide and exceptionally deep, with amazing layering and imaging above similar closed-back models I used to compare them with.
In fact, I actually passed the cans to a friend of mine, and the first question he had for me was “This doesn’t have some new type of surround emulation, right?” Bless his heart, he didn't have a chance to try some really open monsters until now.