So what are you driving these headphones with?
The problem of this headphone is the hybridation between the two cells dynamical and electroacoustical that ask for a steady amount of power on demand but also an amplifier with a very low noise floor : my Sansui alpha Au 607i fit the bill in a way my Sansui AU 7700 could not...This headphone is sensible to electrical noise more than all my 9 others one...
But the source must be the more clean possible, i used a battery dap as a FIXED dac and as a bank for my thousand of lossless musical files ...No more noisy computer bank because this headphone dont want noise at all... :)
And i needed equalization too , ( in my room i used mechanical equalization but here i must use an electronical equalizer... I dont play with it i used it and fine tuned it by ears for weeks of listenings experiments and after that thats all and all stay that forever) because it is necessary to optimize the two cells the dynamical in the bass register under 4000 hertz and the higher frequencies over to reach optimal S.Q. ...
The K340 is a true hybrid in a way the Dharma headphone for example is not, the second cell of the Dharma is a mere super tweeter addition working way over the 4000 hertz of the K340, in the 12,000 hertz if my memory is good, ... And there is NO TUNED RESONATORS GRID inside the shell of the Dharma to create a dual acoustic chamber as in the K340 case...Then one of the only hybrid contender to the K340 is no match at all even if i never listened to it , i dont need to anyway... The array of tuned resonators is the KEY to the S.Q. of the K340 not only the specific modality of the hybrid cells which work equally together and in a specialized way from half the way of the frequencies scale with a cross over transformer inside...
The shell dual chamber need the right pads with the right thickness ( i tried 5 different ) because with the wrong pad the VOLUME of the dual acoustic internal chamber is not optimal...And without punctuated pads the soundfield is not balanced...
All my headphones were damped and i used two different materials inside to control resonance : sorbothane duro 70 and FoQ Ta 102 tape....The plastic grid inside the K340 must be cut off because AKG put it there only for protection of their product not at all for acoustic reason...
I used my "golden plate" ( shungite+copper tape) to filter the RMI and EMI from the amplifier... With many crystals as quartz and tourmaline etc ( here you can laugh i dont mind)
I even use Schumann generators and ionizer but the effect is there but way less spectacular than in my acoustic room ...
It takes all that to reach the potential of this vintage headphone, i paid 100 bucks, and which put any headphone i ever listen to, dynamical, -planar or electroacoustic to shame... They create an holographical soundfield which is completely out of the head natural and speaker like completely... It is a miracle who cured me for the lost of my room...
The only way to upgrade my actual system, will cost me around 20,000 bucks....
I will buy the Choueri BACCH filters dac to improve over my actual basic but very good dac ( dac technology is mature now and good dac may cost peanuts) ... As Dr. Gorike the acoustician physicist who created the K340, Dr. Choeri is a physicist of -plasma working acoustic as a hobby and being a genius he created the ULTIMATE acoustic dac... I will not described why here... And to replace the Top Sansui alpha only the Berning ZOTL tube amplifier will be better and i dont even need to listen to any of these two upgrade before buying them... Dr. Berrning is also a physicist not an engineer who design am,plifier tubes with a complete new technology as a hobby... As you see i trust physicists in Audio they are not there to sell but to invent something new... ...
But i dont need these upgrades; so much happy i am with what i own right now, which total cost is 600 US dollars for the best audiophile system i listened to in my life ... I can die now... But if you had 20 000 Us dollars as a gift for me i will upgrade because i am curious to add Dr. Choueri invention and Dr. Berning genius design to Dr. Gorike K340 unique genius headphone technology... :)
«Truth is a science today who battle for his survival tomorrow» - Groucho Marx 🤓