I listened to these at least 6 different times at Best Buy. Used their equipment, use some of my portable gear. I had the same first-impression as you. Glad I'm not crazy. These aren't for me.

I'll skip these for sure now, thanks...

I'm surprised at your impression of the treble, I found it to be a piercing. Anyway, too bad you didn't like the K550's, seem to be vehemently recommended all over the hi-fi world.
Ps. Best buy sells K550's? Wow...

Did you read what I said about the upper mids? We probably just have different ideas about where the problem spot lies. To me, it sounds like the upper midrange. It effects many instruments that are not in the treble area. Cymbals on the other hand are not exaggerated or pronounced. The problem spot actually probably lies between the upper mids and lower treble.

I also listened to these at Best Buy (Magnolia carries them) and thought they sounded a bit odd. I don't think I have well trained ears, but what I experienced was very well put in your description of the upper mid-range: "plasticky resonant glare." Thanks RD!

I dunno, how long did you burn them in? and what amp did you use, IME AKGs need about 200 hours of burn in, and can sound any manner of strange before then. Also if they are anything like the K242HD, then they are transparent and tend to show the characteristics of whatever they are plugged into way above their own.

Burn in does not change the basic frequency response and has no effect on resonance. And amps/dacs don't have any effect on resonance either. But maybe if I burn them in for 30000 hours they will turn into Omega2's. That would be great. I'll report back in 2 years.
FWIW, these were measured after I wrote this review (I wrote this review, then sent my headphones to Purrin for measurement) and the measurements back up everything I have explained here.

Regardless, from my experience, with prolonged use the sound does change, and things do tighten up. As for the amps, it does matter, it matters a great deal, Most of the AKGs I have tried are transparent in their sonic characteristics, and tend to sound like whatever you plug them into, and this includes adding unwanted resonances which a headphone like Denons will just ignore, to be fair they pretty much dominate most sonic characteristics except for those induced by impedance mismatches.
I am sorry, but I do disagree with you on burn in, it may not change the frequency response, but it does change the sound, something I have noted multiple times with AKGs, but never with Denons. And pads wearing/ sculping to your head during the process also matters.

No, it does not fix resonance that is BS. It is impossible. It's coming from the driver and the enclosure and is unaffected by amp and source. Yes, amps do change the sound, but they can only improve on what is already there, they can't change the driver or enclosure properties, no amp will get rid of this resonant peak in the upper mids/lower treble. The best an amp can do is mask it to some degree, by rolling off upper frequencies, but then you'll really roll off the treble with these phones. And there's no amp that would do enough for me. Yes, burn in does something sometimes but it will never change something like this. It's absurd how everytime someone points out a problem with a headphone, everyone shouts "burn in! better amp and source!" Would be like blaming the tires for the handling of a Prius. Yes, I'm sure fancy tires would have some effect but it's hardly addressing the real problems.
"Most AKG's are transparent"? AKG's are headphones like everything else, and have their pros and cons. These K550's are certainly not transparent. Look at the graph if you don't believe my impressions. They add that coloration to every single album. Which means they are not transparent. And before you call me an AKG hater, I have owned more AKG's than all but a few HF'ers, and speak very highly of many of their vintage models.

My point was actually arguing the merits of burn-in or even mentioning the amps you used. You may have a fair point with the resonances, I don't doubt your critical listening ability. I will get the k550 and spend some serious time with it and then I will be able to confirm or deny your findings.
Transparent is a bad word, uncoloured doesn't exactly work either, not even Stax are truly transparent, but what I meant by it, is that unlike Denons which only minorly change depending on amp, the AKGs change a great deal, and display the sonic characteristics of the amp, thats what I meant by transparent, if you have a word that makes more sense, please tell me, because I haven't found a suitable descriptor for months now.
I'm not calling you a hater, although to be honest I do think you are taking my comments too personally, this is supposed to be a constructive debate, not an argument. And if anything I dislike Harmon Kordon more then you, I personally think its run by execs, which is why every headphone feels incomplete or has some issue, K701, most of the adaptations of the K240 (except the direct renames like the k242.)
I also disagree with the "better amp and source" zealots, synergy is more important, talking of which maybe we should take this convo to PM? and then respond when we have agreed.

I'm not taking it personally, I just strongly disagree with many of these assertions and think they cause problems in discussion of audio gear.
The K550 has a sound to it that it will impart on all amps used with it. So it's not transparent in that way either. It's got some good things going for it, so whether you like it or not will come down to how much it's one serious flaw bothers you. It bothered me quite a bit.

Mediocre when at their best. Painful at their worse (with the low treble ringing). Same experience as you.

Hey RD... Nice review - I like the contrarian views.
That said, could you tell me to what are you comparing these to? That is to say, there is no doubt that compared to an Audeze LCD2/3, these will be crappy. But how does this compare to something like a DT1350? Or a Senn HD25-1 II? Do the K550 bests them or fares worse when compared to headphones at a similar price point?

I'm back, spent a few days with it, burn't in IMO.
And you are correct, for such amazing strengths in a closed headphone (soundstage, imaging, isolation, leakage) it has a serious flaw, it is not really an issue in movies, but in music, it makes artists like Lana Del Rey unlistenable. The resonance drowns out wording, its a real shame, and since IMO you rate a headphone according to its biggest flaw that is not a subjective sound signature preference, this headphone is worth half its retail price. The flaw is that bad. I am disappointed, especially since it does most things so well and so clearly, it should not have shipped like this. 2 stars for music, 5 stars for movies

The DT1350 is better, even the bad sounding ones in just about every way but soundstage and comfort. I can't say about the HD25 since I don't have a lot of headtime with them, but would guess the same is true.

The M50 is also better in every way except soundstage. The only reason you'd prefer the K550 is if soundstage is a huge deal to you, or if you want a bass-lite sound signature AND you're not sensitive to resonant peaks in response. Technically speaking, the M50 is the better headphone in every way. Faster, cleaner decay, flatter FR, cheaper, less distortion, better isolation, better vocals, better bass response, etc.

Indeed, I had put the M50 on (because it was right next to the K550 at the Headroom table at T.H.E. SHOW) to heal myself from the stabbing pain of the K550. Evidently the K550 renders RadioHead and Nirvana recordings into utmost pain.

treble knob, I used it, a lot, like -40% but I thought that was just me, I tend to be treble sensitive - my only gripe with my D7000 atm