I read this thread and my intuition is all the advices are very good...
My own choice is for an underestimated headphone alas! i cannot recommend it to most people...
The AKG K340 ( cost used ridiculous) top of the world in 1978...
The internal set of 5 tuned resonators inside coupled with the hybrid of electrostatic and dynamic cells give a complete natural 3-D soundfield..
Because Dr. Gorike a physicist founder of AKG figured out how to create a dual acoustic chamber inside the shell ( he patented it) using then the difference in timing between direct wave and indirect one making the brain able to create holography impression and outside of the head sound in spite of the lack of crosstalk as with speakers, it is this crosstalk between the speakers and their differential incoming waves around the head with timing differentials which make localization natural and possible, which is way more difficult with two isolate driver on the ears... ...Bass of the K340 are natural et to die for in extension and depth no boominess at all as in my 9 others headphones when there was bass.. ...Highs not fatiguing rival my 2 basic Stax and win...
This is the positive...
The negative to reach this results the K340 is so hard to understand and figure out and drive it takes me 6 months of listening experiments... This is why i dare not to recommend it to people not used to experiment...
But this headphone especially considering the ratio high S. Q. / low price is IMPOSSIBLE To beat by anything , even my past room tuned acoustic with speakers...Because to beat the K340 it takes a speakers set able to give celestial Highs and the deep bass under 30 hertz and an acoustic room for the speakers to shine spatially ... Forget speakers in a living room...
My Sansui alpha AU 607- i the top of Sansui in 1978 is able to drive this headphone more difficult to drive and pickier than any other ... Because it is not only hungry but ask for a supply of potential current the highest possible, his two drivers are picky and way more than just hungry...But anyway it does not ask for costly dedicated tube or electrostatic amplifier as Stax , just regular good one powerful but with very low noise floor because the drivers will reflect the noise as defect imediately... I tried my super loved Sansui AU 7700 and i must changed it for a low noise Sansui alpha with a more refined S. S. design ..
But consider that the price paid 300 bucks for the Sansui and 100 bucks for the K340...I cannot say anything negative AFTER my optimization.. BUt without optimization if you read reviews on the net you will read some which contains negative or reservations ... They dont reflect the headphone limit but the reviewer ignorance about how to optimize this headphone... I know because i perceived all these negative aspects the first day... All was cured after optimization... Think about that : even Kennerton headphone said to me that making an hybrid like that is too costly and too complex and they let go of their project and will not go back ... Now you know why it is the only real hybrid ever made...
i know that anything cannot really beat it...Not on all acoustic counts... How many headphone in the top scale own internal acoustic resonators and hybrid cells ?
Most are single driver attached to an empty shell...His soundfield impressions crush all my other 9 headphone which i could not ever listen again at all...