From top left to right: AKG K7XX, K340, K240 Sextett (MP); bottom: K400 (EP). (PS: K7XX is here on the photos because it is rather more popular these days... So you can visually compare it to the vintage AKG's ) Recently I have purchased an AKG K400 (EP version) headphone (full sized, openback). If you're new to this hobby you might not know but it was one of the legendary headphones that AKG have ever produced early in 90's. It was rather short lived after the introduction of K500, K401 and K501. I can call K400 as the "most secret gem" of head-fi. It is very hard to find enough information about the K400 even on internet! Also this headphone is hard to find on internet second-hand websites because it is rare... Even harder to find is an Early Production (EP) version on good condition (both cosmetically and functionally). Note: There are 2 versions of K400. Early Production (EP) and Late Production (LP). So when I decided to pull the trigger for a pair was right after selling HD58X Jubilee's (one were used the other were NIB). HD58X simply didn't do it for me... I really couldn't get "in to the heart" of the music. I know that there are many fans of this headphone -with all my respect to your choice- I need to tell my situation (do not bash me for this, personal preference...). After selling HD58X's and after the the K400 transaction process, my new toy arrived and oh my... It was really in new condition as stated by the seller! Untouched about 30 years! So I was floating on cloud 69 I have AKG's 2 legendary headphones already in hand: K240 Sextett (MP) and K340 Electrostatic-Dynamic (Bassy Version). I also have K7XX Massdrop Edition (Full Black) which I also like but didn't include in the comparisons. Because this comparative review is only for vintage kings (or queens) ! All these vintage AKG's are made in Austria. K7XX is made in China. Equipments Used for This Review: I have used Geek Out GO720 as a DAC and connected it to my Dell XPS15 9575 notebook. I have attached a Darkvoice TH336SE OTL Tube Amp through the line-out of GO720. I have streamed music either through Spotify (high bitrate) or Foobar2000. The tube choice for the amp were Psvane CV181T Golden for the front and RCA 6AS7G JAN (Military tube) for the back. Some headphones on the review (and photo shooting) did have some modding which is explained on the below: Modding details of K240 and K340 (modded by me): K240 Sextett: Attached with Brainwavz Angled Velour Memoryfoam Earpads, cable is dual entry with Mogami Quad Microphone Cable terminated with Neutrik 6.5mm golden jack plug, old and warn-out dampening back internal foam changed with some synthetic fiber. K340: Worn-out earpads changed with a pair of Brainwavz Hybrid Memoryfoam Earpads. Also there are black velour tape on both sides of the headband (it was opened on both sides so I had to stick them together, glue didn't work... Tape was safer choice). K7XX and K400 were not modded. K7XX stock cable were replaced with a pure silver cable only... Song Selection for Review: For the comparisons the artists (or composers) were selected by @JSBachFan , songs were choosen by me. Why a friend choose artists (composers) for me? Because we owe this thread to his K400 informations on head-fi and while we were PM'ing through message system of head-fi he asked me for a comparison. I have spend around 2 hours and did it for him. Then we thought it will be better to put my review here on the visible part of the head-fi (othervise it will stay on private messages). So if you like this thread please also thank @JSBachFan . If there are errors and if you don't like this comparative review: I am the responsible person! Norah Jones "Come away with me" and "Don't know why" songs. : For overall sound quality both K340 and Sextett are closer to each other (in contrast with K400). Mids are more forward on K400 compared with other two. Sextett and K340 mids are not recessed but the lesser bass quantity of overall presentation brings the mids more forward on K400 (compared to the other two). High region is also slightly more pronounced on K400 so it sounds more open. I didn't find K400 to be grainy or sibilant but when I compare I have noticed that K340 and Sextett sounds smoother on the high region. Interestingly all these headphones sounds clear and with a good amount of detailing. On the micro detailing K340 wins (because of the electrostatic element). Although it looses ground on the bass quality over the Sextett and K400 (K340 bass is a little bit muddier compared to other two). For soundstage width K400 wins. For the depth Sextett wins. Overall holographic image is better on K340. Also layering and staging is better with the K340 (you can almost visualise the instruments or musicians places on the stage). To sum it up: Overall winner is Sextett for these songs. Veni Emmanuel "Wie schön leuchtet der Morgenstern, BWV 436" (comparisons for vocal music): I have visited a church (we have an art organisation here in my city so arranging some places) today and there were people singing/praying so I have a sound image how the hall music should sound. The atmosphere were best delivered through K400. It is like "close your eyes and you're there". For general speaking I love all the AKG's (for different reasons) for this song. K340 layers better with an incredible staging (or positioning). You can visualise the choir in front of you individual singers places, etc. But interestingly K400 delivers the huge church hall atmosphere better. Also staging and positioning were good. Sextett were on the middle ground between K340 and K400. If I have to pick one winner for this song it will be K400. JS Bach "Goldberg Variations, BWV 988: Aria - Remastered" Perfomed by Glenn Gould (comparisons for piano): K400 is the winner here hands down! I have to add: somehow detailing is much better with K400 for this particular song. The other headphones sounded smoother in the high region which may be good for long listening sessions (less ear fatique). As for the tonality again K340 and Sextett is closer to each other compared to K400. K400 sounds airier, more mid and mid-high regions focused. Applause for K400 Top: K400 (EP) Mozart, Symphonien No: 35 In D, K.385, "Haffner", 4. Finale (Presto) - Live (comparisons for orchestral music): You're sitting in the first or second row with K400. It's almost like you're in there with the musicians. With Sextett you're sitting on the 5-8th row. With K340 its in between 3rd and 6th rows. General presentation is better with K400. K340 and Sextett sounded smoother with slightly more bass. Bass quality is better with K400 (although quantity is less). Instrument seperation were best with K340 and K400. Micro detailing were slightly better on K340. If you prefer to sit on the middle of the rows Sextett or K340 might be a better choice. Otherwise K400 is great. I can say that K400 and K340 are on par (for different reasons though). Top: Left K7XX, right K340 Top: Left K7XX, right K400 Top: Left K400, right K240 Sextett After all listening I am tied in between these three AKG's. So can't choose and say one is better. They all excell in some areas... And overall they are all great! For fun factor, Sextett is the safer choice, because it ticks many boxes for musical/fun presentation. But if you intend to listen classical music Sextett doesn't excell on that arena (IMO). I mean it is not bad, actually it is very good, but the K340 and K400 is better for different reasons. This is the problem of having different (or many) headphones... Hard to choose... Top: Left K7XX headband view, right K340 headband view. Top: Left K7XX headband view, right K400 headband view. Top: Left K7XX headband view, right K240 Sextett headband view. Bonus Track (wanted to add this one after review because I really like Saskia's voice): Saskia Bruin "The look of love": Overall winner is Sextett. High-Mid-Bass balance and blending (also quantity) is greatest with Sextett. K400 is also great but it sounds a little more mid-high focused. Have to add: interestingly while listening through K400 when I close my eyes I have a feeling that there is no microphone... like she is in front of me... K400 is a very transparent sounding headphone. On K340 vocal presentation is superb but bass region sounds slightly separated from other frequencies (may be due to hybrid design -headphone has 2 different drivers). Both Sextett and K340 sounds smoother on the high region. So my vote is fo Sextett for this song. In the end I am greatfull for pulling the trigger for a K400 (mine is EP version, it is reported to sound best)! Here are some detailed photos of K400 and its vintage brothers (Review continues on the following part): Top: K400 attached to Darkvoice TH336SE. Great synergy! It also sounds great through solid state amps. Top: K400 (EP) inner part of the earpad. You can see the driver because of the transparent mesh and there is no dampening (filter) foam. I love to see the inside! Top: K7XX inner part of the earpad. You can not see the driver because of the black mesh and foam. Top: K400 EP (Early Production) version jack plug. Fully golden. This design is to distinguish if the K400 is EP version or not. The jack plug can be converted to 3.5mm simpy by unscrewing the 6.5mm tip part. On the other version of this headphone, jack plug design has changed slightly. I have to add K400 (EP) cable is the softest and most flexible cable that I have ever came across on a full sized headphone. Although it is a super nice cable it is prone to tangle. Top: K400 Top: K400 Top: K400 (sexy headphone) Review continues: Comfort: K400 > K240 Sextett > K340 Driving ease (from easier to harder): K400 < K240 Sextett < K340 (K240 Sextett is 600 OHM, K340 is 400 OHM and K400 is 120 OHM. Because of 2 separate drivers in K340 (Electrostatic and dynamic drivers) they happened to be the hardest to drive...) Neutral (Linear) Sound: K400 > K240 Sextett >= K340 Natural Sound: Reviewer gets confused on this part. Hard to tell... It's really recording quality and instrument dependent. Largest Soundstage (openness): K400 > K240 Sextett >= K340 Soundstage Width: K400> K240 Sextett = K340 Soundstage Depth: K240 Sextett = K340 > K400 Soundstage Height: K400 >= K240 Sextett = K340 Hlographic (3D) Sound: K340 = K240 Sextett > K400 Positioning: K340 > K240 Sextett >= K400 Layering: Depends on music... Hard to choose... Generally K340 is very good on this. Sibilance: None of them represents. Bass Quality: K240 Sextett > K400 > K340 Bass Quantity: K240 Sextett > K340 > K400 Mids Quality: All three have great mids! Mids Quantity: K400 > K240 Sextett >= K340 Highs Quality: Depends on music... High Quantity: K400 > K340 >= K240 Sextett Most detailed high and mids: K340 on a slight margin... but others also sounds very detailed! Because of "electrostatic element" in K340, high and mid regions are very detailed. But on some songs K400 sounds more clear... With some singers K400 sounds like there is no microphone in front of the singer and you have no headphone, it's like "singer is directly singing through your ears" -which is really a very enjoyable thing!!! Top: K400 (approx. 30 years old but still accetable design by todays standards) Top: K400 Headband (Synthetic leather) Top: K400 Top: K340 Top: K240 Sextett (MP) Top: K400 (EP) Review final part: Best classical guitar presentation: K400 Best vocals: Depends on vocal and recording. All three can sound phenomenal! But have to add: I tend to like K400 more for vocals. Most enjoyable headphone in general: Depending on music, all of them. Recently K400 gets more head-time. List can go on and on... Lets cut it here. You can ask anything on the comment section. Hope you enjoy! Cheers, Baycode.