I bought this a couple days ago just for curiosity!
That was a collection‘s piece in very very good condition!
Almost 3 driver in it,just like in the 1more tridents!
Just here the driver for highs not a piezoceramic tweeter,its a electrostatic driver/tweeter with a dynamic and with a passive bass membran!
Its made between 1979-89!
They knew what they are doing at that time!
Spacious sound with great detail and imaging,very nice warmish bass!Remind me for the t60 argons just not that dynamic maybe,but i will compare them later!
I compared with the Tridents!I love the tridents too but the akg just a bigger and airier sound with less bass but that bass is perfect for me!
I cant wait to hear on a otl tube amp! Rumors said its a secret tube king,400ohm!I hope soon i can get my hand on my new tube amp!
Its comfy but heavy and oldschool and fuck and i freaking love this headphone too!!!
I love them too - that’s why I own two of them (actually 3 but one is defect and for parts only). They do need a bit of power to shine and the choice of pads is important. For my taste you need some more airy pads (velours, hybrid, fenestrated,…) for them; the bass is otherwise too exaggerated.
The cable and the headphone-cups are actually internally balanced. There are 4 wires (L+,L-,R+,R-) in the cable. Thus you can simply replace/resolder the original 6.3mm plug with a XLR 4pin or a 4.4mm one - but you have to test the layout of course. That way I can use them on more powerful amplifiers/outputs.
Ymmv but I do not really like them on my Darkvoice and Little Dot tube amps; they are already warmish and spacey on solid states and the estat might not react with same impedance-relation to the tube amp as the dynamic driver (my other AKG vintage headphones like the K240 600 Ohm variants sound excellent on tubes). But you should definitely try it.
p.s.: I own the Tridents too but rarely use them.
Thanks the reply 
!
I already ordered a big velour pads for them!
I will try to change the cable or at least the plug,but i never did that before!My set quite bright in a good way!
One thing i noticed,I listened norah jones and diana krall tracks at a little bit on higher volume as i usually do!And i heard some weird distortion noise from the cups!I pretty sure its one of the driver on both sides! I tried with other type of music with same high level of volume but nothing!And i tried with these songs on different headphone but there is also nothing!Interesting,hmmmm!
Have you ever notice that?
No I didn’t have distortion in the AKG K340s. The electrets are prone to aging a bit but I guess you refer to a lower frequency distortion anyway (lower than 4 kHz). I had a similar experience with one vintage AKG K280 (or a k240_sextet - don’t remember exactly) where the passive radiators were damaged in one cup and exhibited a strange resonance at very high volumes.
The K340 is differently built but also has five passive radiators. Probably try to check them for their mechanical stability.
(P.S.: that resonance might be at a very specific frequency - female vocals?)
Edit: you may want to check this with a frequency sweep (like in that video: 1-Minute Audio Test for Stereo Speakers & Headphones - YouTube)
Yeah,its doing that with tracks where is fenale vocalist!
All fine with the test what you send me 
!
I have no idea why doing this on certain songs,its rare but when iam on the listenable volume level no problem at all!
I have owned a pair of these for several months now and I’m definitely a fan. Which version do you guys have (green driver, grey driver, black driver)? I picked up the green driver one as it’s known for being the least bassy/warm and the most detailed/clear. I currently use Dekoni Elite Velours or Elite Hybrids on them depending on what mood I’m in or what I’m listening too, but I have a couple more pairs from ZMF and DCA I plan on trying with them when I get back home since I didn’t bring them with me on the road. Have you guys done any mods or do you guys use any EQ with them?
Anyways, it’s good to see the K340s getting some love!
Ohhh,i didnt know about those colours,but maybe thats why i heard a lots of pair of these sounding differently!
Okey,tomorrow i will check 
I dont use eq and i use that pitted pads whats in the picture!
And i oreded a 110mm rounded velour pads !
Cool! Yeah, the different driver colors sound different from one another with different levels of bass, varying soundstage size, and, some say, different detail retrieval abilities. Once you find out which version you have make sure you come back and let me know. All you have to do is take off the cover and you’ll be able to see the driver color so it’s not hard.
As far as pad rolling goes, I found my K340s to be pretty sensitive to pad changes so you should definitely experiment a bit if you can. Finding the right pads for you is a good way to tailor the sound to more closely align your preferences.
I’ll let you know about the colour !
Yeah,i like changing pads cause thats my only one eq what i use!
Hi!
I checked it! Its green,but i dont know that white material behind the drivers is someone putted there or its original factory tuning !
Yup, that’s the green driver version which is, IMO/IME, the best balanced and cleanest version. I prefer it over the other two. That white cotton/fluff filling is definitely an aftermarket mod that a previous owner did because the K340s don’t have that stock. The question is, do your K340s sound better with the fluffy dampening material or not?
Yeah i think about it but i left there cause i enjoy the sound so much i dont want to fuck around with it yet 
!
But i will try without it and let you know then!
Right now i comparing with my t60 argon’s and the k340 sound for me more spacious and life like! I cant believe they that time could made such a nice sound,i love it!
I think about it i’ll try to find an other pair with green driver for back up!
I dont really care about the more bassy versions,i dont need more bass!Its perfect!
Question!!
The k340s cable is a 4 wired cable! And i have a balanced 4.4 cable which is also 4 wired!
I dont really liked that coiled cable and i thougth what if i cut off the wire under the cup and left about a 10 cm long one! And try to connected with my balanced cable for a try!
But how should i know which wire should go to the others?Or its doesnt matter?
I have planned to do a mod on mine to make the cable balanced and detachable, but I haven’t had time to do it yet. I only got mine back in October and things have been crazy hectic since then. I’m in Europe right now so I can eventl crack them open to help you out. Sorry, bro!
FWIW, to me the two bassier versions sound less clear and less balanced. The green driver has plenty of bass for my taste.
Concerning the re-cabling:
first of all it matters a lot how you wire it! You may even damage your balanced amp in the worst case etc.
If you just want to change the plug to an XLR 4pin or 4.4mm,keeping (parts of) the cable (and not make it detachable), it is relatively easy … in any case you need a multi-meter. I do not remember the exact order/colours of the wires in the cable but you can test that quite easily; before you remove / cut off the original 6.3mm TRS plug/part of the cable, colour/mark the 4 wires on both sides of the cut.
If you do not want to open the cups and measure at the drivers, check on the plug part with the remaining cable: The wire from the plug connected to the Tip is L+, the Ring is R+ and the 2 wires connected to the Sleeve are L- and R- acting as GND. To find out which one is L- and which one R- check the cable to the headphone and test the resistance between the previously identified L+ wire and one of the two ground-wires. The one with about 350 Ohm resistance to L+ is L- the other (i.e. the one with “indefinite” resistance) is R- (cross-check that with R+). If you have any connection between L- and R- on the headphone side, the wiring in the cup has been messed with and it is not balanced anymore.
For your 4.4mm pentaconn TRRRS cable that corresponds to
T = L+
R1=L-
R2=R+
R3=R-
S = not used here (Ground/Shield)
…
EDIT:
found one of my old notes on the cable/wires!
The order of the wires in the flat cable is:
R+ L- L+ R-
of course you have to check which side is “up” otherwise you invert the phases (which is not really dramatic since you do it on both sides)
…
Concering the driver/versions:
Both of mine are green with white resonators as well and both have the fluff filling - they are from different sources and I guess that is not a mod but one of the many(?) versions of this headphone.
Thank you !
This is the kind of useful post that keeps me coming back to forums and trying to be helpful myself. Well done sir! 