Arriving half a week early, my Pioneer HDJ-500K's just arrived today. Not a very reviewed headphone is it? 
The packaging is fairly nice, plastic, but not a clamshell package, it's an actual box.
The alternate language being French, to boot.
Aesthetically, they're quite pleasing in black and silver; they carry with them a modern, refined look. My friend digs the white ones, so he may be picking up a pair soon. Despite their larger-than-implied-size, they still fit quite well on my head.
The leather head cushion and earcups (they're too small to be called that really) were quite comfortable. It needs to be stretched out a bit to relieve some of that tightness, but that'll occur with gradual use. They're more like on-ear headphones rather than over-the-ear.
At 45 ohms impedance, even my older 1GB iShuffle can drive these headphones without a hitch. It's purple too. It's quite comical looking though, with it's massive, sturdy jack plugged into a tiny iPod Shuffle.
The Jack is thicker than the iPod!
Anyways, immediately plugged into my Droid, listening to Mezzo Forte by Minori Chihara, the first thing that hit me was the bass. It felt somewhat boomy, cuing a reduction of bass in EQ. It also felt somewhat unclear, lacking a bit of detail.
The current equaliser settings I had active boosted the low end by a bit too much, despite a heavy lack of doing so; after some fiddling around with the EQ and bass boost settings, the impact was reduced somewhat. Bass does seem to resonate slightly.
Still more bass than I'm used to. But once the equaliser was in place, bass no longer felt muddy to any degree.
Bass became much clearer actually, affording some detail. It didn't feel like the farting bass you get with bass-heavy headphones. Perhaps dynamic range compression helps, perhaps it doesn't.
On classical tracks, such as THE UNIVERSE from Gundam Unicorn, the headphones delivered strings, harpsichord, and the piano quite well to paint an image of peaceful sanctuary. UNICORN brought with it powerful drums and drama, quite nearly placing me within the drama of the show itself, inside the cockpit of the RX-0.
For DJ headphones, the highs and mids didn't feel too lacking, despite a somewhat dismal frequency response graph. Looks good if I feel like using it for a gig.
Partly related to the treble boost I have. The clarity though, depends partly on the quality of the source.
Treble definitely wasn't lacking with the boost in place, and overall clarity was quite acceptable for headphones that are designed for 2 purposes, DJ'ing and everyday listening.
They're somewhat forgiving to sources, plugged into my friend's Macbook and listening to 128kbps mp3's(of rap...). But the difference in quality is noticeable when you jump from 128kbps mp3 to 320kbps mp3's, which were the best I had on hand. As far as sound stage goes, these felt like an improvement over my Backbeat 326's(still nice in their own respect), giving me more of a definite idea of where the singer and various instruments were in the music and widening the image. It may be logical though, being compared with IEM's.
Overall, quite a nice buy as an $85 piece from an authorized dealer. The white ones will run you $99 instead from an authorized dealer though, do note that. The magnesium core construct feels quite sturdy, despite the fragile outward appearance. The headband has the same feel as the back of my Droid, a nice, grippy ergonomic feel. The more I use it, the better it sounds. I'll update once I'm done burning it in, but for now, I'm a happy junior head-fier.

















. Bit muddier in vocals and highs but still nice to listen to. I did note some hissing, but that was actually due to DSP manager. I guess that faint hissing is present even in non-blur based sound adjustments.

