The AKG K550 revisited.
At the time, shortly after I bought my Audio Technica A900Xs I had auditioned the AKG's and I felt my choice for the A900Xs was the right one. I felt the K550s had this weird grating low treble peak that showed up just too often, unlike the low-treble/high mid peak of the Denon D5000s that only got aggressive ocassionally.
The price at the time for the K550s was 300 euro, the A900Xs I got for just 150 euro.
Fast forward in time: the K550 (MKII) now sell for 150 US dollar and encouraged by some reviewers who mention that the MKII version solved the problems of the MKI, no longer a grating treble peak, better clamping and fit and slightly increased bass I took the shot and bought them.
 
Maybe my ears have changed or the K550 MKII really is an improvement over the MKI version, I dunno, but the low treble peak just isn't there anymore. I tried the most difficult recordings with soaring highs and big contrasts in dynamics. Baroque violin concertos, where the lead violins are recorded so up close that it is impossible to get away with some aching or grating. And some choral works, where most crescendos will make the headphones loose control and start to ring a bit.
To name a few:
Geminiani Concerti Grossi (After Corelli) - Chiara Banchini
Bach Violin concertos - Elizabeth Wallfisch
Haydn Die Schopfung - John Eliot Gardiner
Haydn Die Schopfung - Rene Jacobs
 
With the violin concertos mainly the slower adagio parts are the difficult parts, because it are HIP (historically informed performance) recordings in where the violins play without vibrato, so the long legato lines, close-miked can grate very easily.
The difficult choral parts are the ones in where the choir all of the sudden sing much louder. 
None of my headphones, including the Sony MDR-Z7 (which is universally qualified as extremely inoffensive sounding) handle these recordings without problems.
The AKG K550s don't sweat, they sound so even over every frequency.
Therefore they surely must lack something? Maybe a soul?
Nope. They just don't loose control, that's it. 
They sound big, have a great soundstage with good width and depth, excellent for classical music. But they don't sound thin and too bright with smaller scaled music, something I do feel ocassionally with the BeoPLay H6s.
The bass is big enough to give music body...talking about body...if I must find something the K550s lack a bit is some low-mid warmth or coloring, something the A900Xs have and what make their sound one of a kind. But the A900Xs can sound grainy, something the K550s never do.
 
All those years I have dismissed a pair of headphones that are easily one of the best pair of closed headphones under 600 US dollar...and they can be had for a mere 150 US dollar.

Lumia 640 LTE
I never owned a portable device (apart from a Sony Walkman in the 80's) because I never felt the use of it.
Just out of curiosity, not expecting much, I plugged my Sony MDR-Z7 in my newly bought Lumia 640 and started listening to Youtube videos and Spotify. "Pretty good sound", I was thinking and I decided to import some music to my phone. I bought an 64GB Micro SD card and soon regretted I hadn't bought a 128GB card right away, because simply put the sound I get is superior to any CD-player/ amp combo I ever had or auditioned. 
The sound is neutral, open and very natural, not a hint of grain or distortion and because the MDR-Z7 is very sensitive I never have to up the volume to the extreme, the highest volume level I ever set was 17 (out of 30 max).
The Lumia 640 is able to play every format out there, including FLAC and OGG. The standard music app XBOX music does not, but there are excellent apps out there that can without compromise. There even is an app "Teh Jukebox" that plays gapless (something Windows 8.1 does not do natively) and does this flawless with FLAC, OGG and most MP3's, unfortunately not Apple's AAC (M4a), only a few tracks play gapless, most not. But realistically there are very few albums I have that desperately need gapless playback, so this is not an issue for me. But it is nice to know that it is confirmed that Windows Phone 10 OS gets gapless playback natively. It is about time!
 
Although the Xbox music app plays just fine there are better music apps out there, with better interface, better handling of metadeta/tags and more features. I'll end this short review with four great music players
 
Teh Jukebox ($2,99)
For the music enthusiast that demands gapless playback.
Although the user interface isn't as polished as some competitors it obviously plays FLAC and OGG gapless, but also most of the MP3's and some AAC's. That's all you need, isn't it? The app is fast and stable. it doesn't build its own library but uses the music folder of the phone and SD card, which is fine because it will always play tracks of multi disc albums in the correct order.
You can make playlists and even rename and delete files.
 
    
 
Core Music Player ($1,99)
My favorite player. It does not support FLAC, It also supports FLAC but although 256 KB/ps AAC is acutually good enough for me, I cannot hear differences between this and a lossless file.
The interface is slick, the app is fast and stable, You can make use of the music folder only or you can make use of a library if you want which is build pretty quickly. It then organizes the files in the usual groups album, artist, genre etc. And also adds mini albums in the lists, which is nice. A downside is that it sorts the complete library alphabetically, including the album tracks. I prefer the tracks of an album to be sorted in the order of the album. Especially with multi-disc classical albums (like operas). It however plays the tracks in the correct order if you not open the album first to select a track, but directly click the album to play. It then also plays multi-disc albums in the right order. (Something XBOX music and many other app do not do, they will sort the files numeric, disregarding the disc tag/metadata, so it will play track 1 of the three discs first, followed by track 2 of disc 1, 2 and three. You do not want this to happen with an opera!)
You may as well disregard the library all together and just make use of the music folder (phone or SD), which has no issues with wrong sorting.
There are many customizations, like different color themes. You can make playlists. Make use of a timer. Things I don't use btw.
 
    
 
ModernMusic. ($1,99)
Another slick player. 
This would be my number one player if it would be quicker in building its library. A serious annoyance is re-syncing the library, while adding only a few new tracks it completely syncs from scratch again, rebuilding the damn library track for track. Core Music Player when re-syncing only searches for new tracks and is so much faster.
And ModernMusic only makes use of a library, you cannot directly browse the music folder on the SD card or phone.
But having said that, the player is gorgeous. Also fast and stable once the library is build. The player plays multi-disc albums in the correct order
 
   
 
Loco Music Player (Free)
 
Great player. Makes use of a library and Music folder of phone, SD card and you can even choose the One Drive music folder.
Again fast and stable and the player itself is nice looking. But the library is pretty awful. When selecting artist it not only shows the artists in alphabetical order, but it directly shows every track by that artist. If you have a large library prepare yourself for endless scrolling. Yes you can select a letter for a quicker access, but still you find yourself scrolling a lot longer than with every other app out there.
Luckily you can access the music folder as well and although visually not as nice as Core Player and ModernMusic, it just works. Multi disc albums are also played in the correct order.
 
   

These headphones generally are excellent.
They possess this remarkable mixture of openness and intimacy at the same time.
There’s a true sense of soundstage, with a good width and depth and still they manage to sound pretty direct, upfront and dynamic.
Their tonal balance is well judged, with a (slightly bigger than) slight emphasize on the low mids and mid bass, which gives any music a pleasant body, I particularly like this with classical. The highs are spot on, I never encountered any nasty sibilance.
 
As said they generally are great…when I’m feeling fine that is, and luckily most of the time I do.
I am greeted by a big cloud of effortless and dynamically fluid music reproduction. 
Everything to Mahler symphonies, Baroque concerti, indie music, singer song-writer etc. sound fantastic.
Instruments sound beautifully textured, I like the rasping at my ears of brass, low cello and distorted guitars.
 
But this texture is dry in nature and this dryness can become metallic when I am not feeling 100%. Then this textured sound gets irritating and grating. I have to stop listening or start passive listening - with this I mean focus my attention on something else, like browsing the internet and not directly at the music.
My Denon D5000s are brighter and with some recordings even colder sounding, but their texture is not as dry, instruments sound softer (not rounded per se) and although the D5000s are more prone to sibilance, they are generally less fatiguing.
But I don’t see this as a fault of the A900Xs per se, because at this price point there are compromises to be made. You can’t have it all.
And when my ears are up to it, say 80% of the time, this dryish texture is very pleasing.
 
What I also like about them is that they - just like the Denons - are easy to EQ without sounding off.
A900Xs mids can become shouty with recordings that have big dynamic range. Sopranos, woodwind can distort slightly (I suspect because of their closed design, the sound cannot 'escape' so to say), so with classical music I sometimes lower the mids a bit and with this it gives the soundstage a little more depth as well, yes artificially but it works.
Just like I up the mids of the Denons a bit to make the sound a bit fuller with some recordings (but only after I have used the A900xs for a long period D5000s recessed mids are noticeable)
 
A lot has been written about A900Xs fit and comfort.
It is true, they are not the most comfortable headphones, they sag too low on my ears, but I got used to it.
Overall these are excellent headphones.
 
Edit:
I forgot to mention that these headphones can be truly magical with vocals, both male and female!
And I am doubting a little if I weren't a little unfair by mentioning they can sound slightly hard because of their dry texture when I am physically not 100% ok...wouldn't this be the case with a vast majority of headphones?

I find it difficult to get used to the sound of this little amp.
In comparison with the amp I used for years, the headphones-out my old faithfull Marantz PM7200 the sound is superior in many ways.
There's more depth, a cleaner, more fluid tonality, better layering of instruments and finally no more humming/buzzing of the transformer, the main reason I got this amp.
But the sound isn't as wide. With some recordings my ears miss something, especially my left ear craves for more sound, it wants the music to fill out the left channel and beyond.
This makes for a hard listening at times, but to be honest, objectively the difference in width is really small, I am just so grown with the sound of my old amp, it is just like an old habit I need to get rid of.
Or maybe not? Time will tell.
I give this little V-Can some time to grow on me, because it has lots of good things going for it.
I'll update this review over a couple of weeks.
 
Update:
I will return the little amp. There's a clear channel imbalance. I tested this with my Marantz amp, when turning the balance control knob slightly to the right it gave me the same sensation I got with the V-Can, my left ear begging for a little more sound. It's a pity because the overall sound is really excellent.
 
So this review is no longer valid, because it is not fair to rate a faulty unit. Therefore I ask the moderator to delete this review in time.

Audio Purists steer clear of them, because they need to be EQ-ed to get the best out of them, because one thing you will immediately notice is the sheer lack of treble. This is great with harsh recordings but even than it just sounds unnatural to me, give me sibilance over a huge treble roll-off anytime.
The lack of highs is a real shame because overall the tonality is spot-on, instruments, vocals all sound very natural and real, they have enough warmth and body to be called musical.
Luckily EQ-ing is very easy, iTunes preset "more highs" simply does the trick and with it the sound opens up and is just excellent.
 
Their soundstage is not very big, but it is cohessive and intimate. There's just enough sense of the space and the (room/hall) acoustics in recordings, not exactly 3D, but definitely not flat, like the Audio Technica M40Fs I had, their sound was very upfront and wide but extremely flat (in the sense of space and room acoustics)
I like Rolands forward presentation without sacrificing spacial information, it is very engaging with rock, but with some classical music, say Baroque music as-well.
 
I never heard the Audio Technica M50's which supposedly are very similar, but I certainly prefer the Rolands over the Shure SRH-840s, which sound distant and compressed in my opinion, maybe because they are very mid-centric.
In comparison with my D5000s they are no match, the Denons are better at everyting (well except isolating external noise) but their easy nature is very likeable and I could easily live with them if my Denons would break or would be stolen or something else out of the ordinary.
 
They sit very comfortable on my head, the clamping force is just right for these kind of phones. They don't need to be placed in a certain angle on my head or anyting to get a better (or different) sound.
 
Last word about their looks: aren't they lookers?!
 
EDIT:
Just to add something that's worth noting. These headphones are extremely sensitive, this means they actually need a proper amp, because otherwise you may hear static noise or some hum. And be careful with the volume level, they need very little current to sound loud, and because of their easy going nature you are bound to play way louder than is necessary.
 
EDIT:
Added half a star.
They are getting better and better or maybe I am beginning to like them better and better.
I never heard Trail of Deads' Lost Words and Source Tags & Codes this big and exciting sounding!
They get way more air time than my Denons right now.