The bottom line is that these AKG K550's right out of the box sound like K702's with a +2db boost to all frequencies lower than 500Hz. So if you favor the AKG flavor, slightly thin-sounding mids and bright highs, and need closed-back, look no further. Comfort is off the piston - The Denon D2000's come close, but these feel lighter, and the DT770 consumer editions clamp a bit more. These make room for even the largest ears, with maybe perhaps just the slightest brush of the driver foam touching, and yet I still don't feel any papercut-like pain to the edges of mine (unlike the M50). These get a 5/5 on comfort for me, and no, they don't squeeze the dome like a vice.
Isolation is good, not a complete canceling of external sounds but they do somewhat mute them. The earpads are removable and the controlling of leakage of sound blows away all the over-ear competition except for the Pro700MK2's, they are unbelievably neck-and-neck. You will be surprised if your tunes were cranked and you hand closed the cups together, they emit a soft tone of your music - fantastic (Here's a chart to illustrate further - Audio Technica AD700 > Beyer DT880 > Beyer DT770 (non-pro editions, believe it) > AKG K702 > Beyer DT860 ~ DT990 > Denon AHD2000 ~ VModa Crossfade LP > Audio Technica ATH-M50 > Beyer DT770 pro 80ohm > *AKG K550 ~ Audio Technica ATH-PRO700MK2 > Etymotic ER4P). The build is straight supreme - the headband being metal with soft touch pieces around some parts. No detachable cables or a carry case at all - boo. A 1/4" screw-on adapter is included.
I find that the highs can be bright, but to me, only at louder volumes. They are more than tolerable even if you're watching movies. I find them to have plenty of detail and definition, but with that slight tizzy sound that the K702's have. The mids are present, they don't feel recessed at all - this was demonstrated with some gunshots on Modern Warfare 3. The M4A1 has some nice weight to it and sounds very crisp (and loud) on these K550's. I did notice that around the 1K mark, there is a slight boost that makes the upper bass/lower mids have a hollow-cup like sound on it. It's not distracting but it is there. The mids are crystal clear in my opinion, but do sound thin. Vocals and instruments have great separation and imaging, but the notes in itself sound a little pinched. Switch between these and a pair of Crossfade LP's and you'll know what I'm talking about.
The low notes come through clean and slightly punchy. The Denon D2000's, Crossfade LP's, and the Pro700MK2's definitely have these beat - by at least 3db. But I think these were designed to be as flat as possible, so these are not bass-monsters (Damn!). These K550's are like a regular Whopper sandwich, while the aforementioned three are like a triple-stack heart-attack - with the Denon being a touch lighter than the LP's or MK2's. There's some meat on there, you can taste it, but it might not feel you up. It certainly doesn't me, so I reached for my good friend EQ, boosted the bass about 4db, and now, I'm satisfied. Movie soundtracks sound much fuller and alive with some extra bass on these.
The soundstage is awesome. 3D, like it should be, and with great positioning. I played MW3 infection and actually got the drop on some infected. I still suck, but the K550's are no slouch in the gaming area. There's plenty of detail throughout the spectrum - you can easily locate footsteps fore, aft, back-left etc. like a champ. Movies are equally awesome, although when cranked the highs seem to overwhelm a little so I keep the volume slightly lower than what I had it with my MK2's. AND, speaking on volume, these can bump 117db in the cup. That's loud. I like that. Some others do too.
AKG has done a good job. I used to be somewhat interested in the other K242-272HD models, but the reported lack of bass made me stay home on those. These are not bass-light, but nor are they bass-heavy, nonetheless, hardly any other closed-back that I've had can match the comfort - and they sound great too.
I'm impressed with these and will definitely keep them, for games especially and for times when I need comfort in the closed fashion. I will continue to update this, with more comparo's and if the sound changes as more cooking (burn-in) is applied.
Edited by GN3RAL KARL - 3/3/12 at 2:14pm