I looked high and low for good set of closed back headphones, as my current job almost dictates the use of exclusively closed cans. Also I needed something for my bedroom recording to keep pace with all sources I have at hand without ever needing amplification.
DT-250 came right in - first I was contemplating DT-770, but having read mixed feelings about the treble intensity and since Premium range was discontinued, they were the next logical choice. Being vintage AKG fan, I could have aimed towards K550 or K271 but those had drawbacks I was reluctant to accept. Surprisingly, DT-250 were hard to find as everyone seem to be pushing forth the trio 770/880/990.

As my gear is of varying output impedance, some sources even above 20 Ohms, I wanted at least 250Ohms, but possibly not at expense of sensitivity, which would have to be high enough to accomodate low-voltage sources. Again in this regard, DT-250 in their 250Ohm variant have not disappointed. With 100dB/mW rated sensitivity at 1kHz, they can be easily driven from sub-1Vrms sources, such as Sansa Clip+ up to ear damaging levels.

In regards to comfort and sound, they sound very balanced, not one part of the spectrum sticks out. Some might have noticed the ever so slightly pronounced trebles, but coming from K240DFs, I don't find them overpowered, unlike DT880 (both 250 and 600Ohm versions). My only complaint would be aimed towards the bass, it's somewhat less defined compared to K601, but that could be due to the construction and something to be expected of closed headphones. I don't enjoy forward bass as others might, in fact having it slightly recessed is what I found useful for long sessions. DT-250 do not have forward bass, and it's level with the rest of the spectrum as with K601. Spatialization leaves something to be desired, the 'soundstage' lacks both width and depth of semi-open or open headphones, but they make up for it by reproducting textures with incredible accuracy.
IMO, while narrower, the soundstage is still better than DT880, which were very confusing with familiar tracks.

The clamping force takes a while to get used to, and for people with glasses I would strongly encourage to try wearing them before purchase. Some people might have problems with fitting their ears inside the cups, there's virtually no space reserve. My ears fit the just, but not without wiggling the cups a bit.

Overall I would highly recommend the DT-250 to anyone who is on market for good closed back, durable and not overly expensive set of headphones.

Edit: After 5 months and over 200 hours of listening time my opinion changed slightly - and they deserve full 5/5 score hands down. More later

I thought about getting DFs as a present after passing driver's exams. Read those very few reviews online, which were generally a mixed back of helpfulness. Then I took the bullet and said, yes why not since I found a pretty good deal on ebay.de. I put them on and my jaw fell. The sound was so right, accurate and spot on, something I haven't experienced with any headphones before (K702, DT880, DT770, K701, K240 MK2). As the time passed, I sold most of my other HP as DFs superseeded them all. 
 
The build is very similar to today's K240 Studios and MK2s, however DFs were made only in Austria, so all the materials seems sturdier, better looking and well made. My version came with genuine leather pads as well (no cracks), albeit fairly worn. DFs as well as Monitors do not feature miniXLR socket, the cable is securely soldered in. 
 
Ah yes, the cable. It was only when I replaced it, the DFs came alive. 
HA, caught you there Andy - you were audiophool and cable placebophile all along! 
 
Not today Mr. Weasley. Upon careful examination, measurements and blindtests, the stock cable was found to be very noticeably altering the stereo image. First time that happened to me. 
Fortunately, the remedy doesn't have to be expensive. I grabbed Van Damme Starquad for $2/metre, which I used before as mic cable and had great experience with. It was some work to fit it in there, but 2 hours later and my DFs were recabled. 
 
Comfort-wise, DFs along with MK2s were among few headphones I could wear for hours without strain.
 
Now for the sound. DFs were marketed as "Diffuse field equalized to meet strict IRT specifications", and honestly they do sound like a near-field monitors in a small yet reverbant room. The spatialization aspect pretty much couldn't be better. It might not "impress" the listener as K701 do, certainly not on a first trial, but over time one starts to pick various elements in the stereo image much more precisely placed than with most headphones. The soundstage feels spherical, not excessively wide, retaining all three dimensions, especially depth. Elevation aspect isn't very pronounced, but still noticeable. 
Trebles feel very natural and extended beyond human hearing range. Mids are right on spot, natural as they should be. Bass is there, not well extended, but controlled, not muddy, and plays very well with the rest of the spectrum, more so with acoustic genres. 
 
The headphones are rated 600Ohm and 88dB/mW, which means you need an amp with lots of voltage reserve. Those who like it uber loud should aim for more than 6 Volts into 600Ohm. 
For the rest of us, I found 2 Volts ceiling is enough to enjoy any sort of genre with enough reserve to boost quiet tracks. Most today's DAPs should handle 2Vrms into 600Ohms. For those which don't, O2 is a perfect remedy. 
But even at just 1 Volt it's reasonably loud. 
 
Overall the K240DF are one of the most underrated HP out there. I highly recommend anyone to give them a listen, possibly with different than stock cable. 
I'll expand this review with more comparisons and photos shortly.

The following review considers Clip+ with one of the latest Rockbox builds. Any features mentioned therein are from Rockbox frontend, not Sansa.
 
Clip+ won my annual price for the most influential product of 2016 in price/value ratio. Granted, it was released in 2009, but finally I got it last year, and it was instant winner, topping even the most awesome buy of AKG K240DF.
 
At first I needed something to replace the aging SX480 CD player, which still does work, but I'm not that avid "CD burner" nowadays. Fiio DAPs are just too heavy and large to be convenient for portable operation, so I opted for Clip+, despite the reports of CPU chirping in the headphone out (which none of my units experience).
Yet Clip+ managed to overthrow one DAP after another. In the end, I kept only Clip+ and I couldn't be happier with it.
 
So how did that happen?
 
Firstly Clip+ boasts with higher-than-average battery runtime of 20 hours. With special beta Rockbox, it's possible to get even 30 hours when playing back FLAC at 44.1kHz. Both my Fiios (X3II and X5II) top at 12 hours max. To get more, power banks need to be introduced, which increase weight and size, pushing them into "transportable" category, rather than "portable".
When Clip+ arrived at the scene, naturally the first thing to do was listening and comparison test. I compared Clip+ to X3II and X5II very extensively for over 2 months and found no verifiable improvement in sound, not any that would justify the extra price or power consumption. As I'm no placebophile and focus on more "down-to-earth" features than fantasy-like promises of "better sound" at all costs, suddenly Fiios lost precious ground. There are still reasons to keep them (DAC functionality, DSD, automatic sample rate switching), though not for the majority of uses.
 
I desperately wanted WavPack and Ogg-Opus since 2015 and Clip+ delivered in full and also added IT, S3M, XM, MOD module support and MIDI playback with its own soundfont. No other DAP regardless of price (yes even HM-901), at least those I checked, come with Opus support.
To those who don't know what's Opus - it's lossy, compressed format, currently with the best compression vs. quality ratio. Even 128kbps sounds incredibly transparent. Usually only vocals give it up.
 
Clip+ unlike other "high-end" DAPs also comes with advanced features such as crossfeed, HAAS virtual surround, speed control, 10 band equalizer with adjustable Q, channel operations, ReplayGain, time-stretching and onboard compressor/limiter. Constructing playlists on the go is super easy, and they're stored in m3u8, thus fully compatible with WinAMP or Foobar2000.
There's 100% true gapless playback on all its supported audio formats, except modules. Where Fiio would pop during track change (lossy formats), Clip+ jumps to next track without any sound.
And for good measure, voice and FM recorder is included too. Built-in microphone is no high-class, but it's easily replaceable for say Primo EM184 or EM258. Both achieve good clarity for voice recording and even some music. Clip+ offers lossless formats for recordings, including WavPack.
 
Where Clip+ slightly lacks, that'd be the department of power. Both Fiios achieve over 100mW figures into low impedance loads and very impressive voltages for DAPs.
2.67V_rms for X3II and 2.82V_rms for X5II. Clip+ runs at 0.82V_rms maximum - all figures are into unloaded output (5MOhm).
However considering that Clip+ amp stage, integrated into its SOC, together with DAC, runs for couple miliwatts, that's fully understandable. In another words, Fiios consume over 40 times more power.
 
There are likely more features I have unintentionally left out, but for me, the Clip+ is the best DAP I have ever owned, hands down. If you don't have it, you can still get refurbished unit, just like I did for about $60 for 8GB model.
 

With somewhat high expectations I auditioned a pair of original HD800 today for about 90 minutes (enough with correct test methodology).
Just when the first track started, an idea came to mind that those sound close to modded AKG K702. Supposedly though, some headfiers refer to HD800 as being in "different league" and thus incomparable to headphones costing magnitude lower. Actually it was a very close call.
I divided the listening test into 3 parts - listening without reference, headphone and source comparison.
 
In the "just listening" part, HD800 did somewhat well, managed to uncover this "micro detail" of musical performance (classical genre tested), however, concluded in comparison with AKG K240DF and K601 had the same level of detail, in specific cases, even higher than HD800.
Listening to HD800 becomes tiresome after just 20 minute session, the clamp force is okay, but ears become sweaty fairly quickly.
What I also noticed is how more efficient HD800 were compared to AKGs.
 
In spatialization aspect, they pretty much mimic K702, immensive width, shallow depth, thus poor mono performance (approx. 10% of the image). I prefer both K240DF and K601 in that aspect - circular "soundstage" not as wide, but with depth and good mono compatibility (20%).
 
Extreme quiet listening (45dBA) surprisingly retained most of the qualities of the headphone.
 
Bass (20-100Hz) is more pronounced compared to K601, but also less accurate. DFs are by design bass-light so no comparison there.
Mid range (100Hz-1kHz) retains same qualities compared to AKGs albeit being approximately 2dB quieter
Vocal range (1kHz-4kHz) this might be one of the stronger points of HD800, it's more neutral than AKGs
Highs (4kHz-18kHz) that 6kHz 4dB bell gets tiresome quick, but unmodded DFs are suffering from the same issue. Mod should remedy this in both cases, however get much more complicated with HD800.
 
In short, I enjoyed Music of the Spheres by M. Oldfield more on K601, where all parts of the spectrum played well with each other and still managed to extract all this "micro detail" same as with HD800.
 
Moving onto source comparison (this'll be real quick). I tested Fiio X5II and Sansa Clip+, both direct and fed through TLE2062-enabled Objective2. Regardless of where I plugged the HD800 they sounded always the same. I also verified this with switchbox, where switch times are no more than 2mS.
In conclusion, I wouldn't buy HD800 for the €1100 price tag. To me they seem to be worth €200 maybe €300. One could get similar sounding signature with modding K702's bass ports and K702 are nowhere near the MSRP for HD800.

Edit: From the start I found the 112dB/mW claimed sensitivity not entirely true, and today I made an comparison. Monk Plus is far from the claimed sensitivity, reaching no more than 100dB/mW at 64Ohm impedance.
The way I did the test was using headphones with known and correct sensitivity and impedance and match them to Monks in terms of volume. DT-250 were used for that purpose. At 1kHz, 5.7dB had to be retracted from Monks to achieve same volume level. As DT-250 are 250Ohm at 100dB/mW @ 1kHz, this post-calculation leads to the same sensitivity level, only at different impedance.
So Monk Plus are 64Ohm and 100dB/mW, or 112dBV not the overstated 112dB/mW.


Back in January 2016 I purchased the original Monk as presented by VE at that time. At first I was a bit skeptical, not just for the price, but no earbuds I have had were any good. They turned out to be amazing success, I went that far as to completely replace my portable gear and now I use only Monk when travelling.
In September I gave out my 2nd backup pair to one of my friends and they love it, but that mean I had to get new backup.

Turned out Monks were discontinued and replaced by Monk Plus. Unsure of what was changed I wrote a PM to zhibli06 here. No response, so I went to Aliexpress and used their chat system a week later in the morning to compensate for time differences. VE appeared online, yet never addressed my questions 3 days in a row. Neither their Aliexpress page, nor description on veclan.com list any sort of technical data that could help one make informed purchase. Most important info like impedance and sensitivity was completely missing. Only 4 pages of how Beats are useless, how to proceed with the purchase, not to open any disputes (all that understandable), microreview and bunch of photos.

Finally I decided, what the heck, the original isn't available anyway, so I ordered 3 pairs of royal purple. Despite the ongoing Christmas rush, they arrived fairly fast, only in 3 weeks.
Impedance was the first thing I checked with my DMM and surprise, it's 64Ohm! The originals are 32Ohm/112dBm. Not saying it's a bad thing, but I prefer to know such info beforehand so that I can check with my gear how much power is going to be required. In sighted comparison, both sound very similar, only Plus appears a bit quieter at the same volume, likely due to increased impedance, but only a bit. Plus also feels a little more revealing, but with earbuds it's always about the right fit, so I may be making things up.

Overall I'm satisfied with the purchase, I just wish VE could update their webpage with some technical data, as this may turn objective/technical people away.

I was looking for something to fill in the gap between K240DF and K240 Monitor. Severely disappointed by alleged "successor", K701, I postponed purchase of K601 for many months, until I finally gave in.
And boy I was wrong.
In short K601 are the real successor of K701. Backwards as usual, AKG, but they did it.
There's literally nothing in the sound that could be improved upon...not to my ears at least. That however doesn't mean it's good for every usage.
 
Sound-wise, it's as flat as it can get. Non-saturated bass, balanced trebles and mids, just right. Perfecto.
If you examine the frequency graph on headphone.com, you'll see there are only very few dips from 20 to 10000Hz, otherwise it's clean, almost straight line.
 
Some reviewer hinted at "hard to like the sound". Let me explain what he/she probably meant by that.
K601 have almost no early reflections, just as open-back headphone should, but in fact even less than average. Therefore the "meat" of the sound is missing from some recordings as headphone shell doesn't contribute to the sound at all. Tracks are usually mixed on studio monitors in well treated room, so the engineer counts on some ER to be present in playback conditions.
That's not true for K601. Correct term to describe this effect would be using this sentence - K601 are dry sounding headphones.
 
As for comfort, it's comparable to K240, only the ears don't sweat as much. In other words, very comfortable.
 
Volume-wise, K601 are not the most efficient, but higher impedance helps to achieve lower currents and usually leads to lower distortion on amplifier level. Generally speaking, as long as your source is 1V RMS or above, with 15Ohm output impedance or lower, you're fine. At 1V you should be able to achieve 101dB, which is waay more than enough.

I don't usually do hands-on reviews, but in this case I'm quite certain. I got my pair of HD414 for a bargain price, still in EX/VG condition, only a bit dirty on the inside.
What originally caught my attention was 2000 Ohm impedance. I was like...really?!? Apparently someone caught up to the idea of high voltage/low current, which was perfect for me. At 2kOhm and 102dB/mW this looks like the perfect set of cans to be driven from virtually anything, even line outs!
Unfortunately while this looks great on paper, the light-speed fast transients that could result from such high impedance are not there.
Sound is vastly oriented around mid range, with no bass and only bits of treble. Kinda reminds me of Koss Pro4AAT. Non existent soundstage and highly attenuated detail.
As for comfort, my experience could be a bit biased as the pads are quite worn off, but HD414 are by far the least comfortable cans I tried.
 
But there is still hope.
I'm quite certain this veiled, uninteresting, degraded sound signature is the symptom of that headphone cable. Honestly I didn't see anything that'd measure worse than this.
Almost 12Ohm resistance over 2.5m, 180pF capacitance between all three wires, straight (not twisted) pairs and no isolation. This has to be the worst cable I've ever seen and is bound to negatively impact sound.
Once new cable is built, I'll update the rating to reflect the change.
 
EDIT:
After applying 4mm of soft foam onto the worn off pads, the good sound finally started to shine through. Treble started to appear, and surprisingly (or not), very clean.

I was quite disappointed with my DT880. I thought they'd make for excellent christmas present, but I was really wrong.
First thing I noticed is very pronounced treble. While it might be OK for listening, e.g. after burn-in and "you'll get used to it", that was not why I got the headphones! I bought them for music production and that treble peak would push me towards equalization the wrong way, which is simply unacceptable for reference headphones.
Reference means something that is uniquely and objectively transparent, from which can one "reference" sound. 
Mid-range is severely attenuated, I didn't hear much of it so can't comment on this.
Bass, that's probably the strongest point. Very deep, but feels detached from the rest of the spectrum. 
 
It fell short on all of the vintage "truly reference pairs" I happen to have - AKG K240DF, K240 Monitor and K141 Monitor, all in 600Ohm.
96dB/mW sensitivity is rather good, there were no problems with volume on all my devices, including portable players. Amplifier, while truly not necessary didn't improve the sound a bit (JDSLabs Objective2), that further proves it's transparency, but not headphones.
 
I tried listening at low volumes close to 50dB, but the spectrum problems were there, clear as day. 
 
As for soundstage, there are hints of 3D in it, but it's too narrow and shallow to precisely position instruments. K240DF is way more reliable in this regard, with clear distinction between front & back, which makes orchestra positioning in DAW much easier. That term Diffuse Field Equalized was not thrown there in vain. 
 
Overall I cannot recommend this pair. Good for audiophiles, but not for producers & engineers. 

I owned two PA2V2 and while it's good value amp, it had far too many flaws to my liking.
Gary however provided excellent customer support throughout the whole time.
 
Ended up with O2 and I'm happy so far.