I apologize beforehand if I should have started a new thread, but I figured folks with a Koss ESP950 or Koss ESP95X like me might be curious about the earlier Koss models. If you try this, besides the risk of electrocution, Spritzer has stated before that these weren't designed for pro bias - so I may be slowly killing these Koss ESP6.
When I first bought my Koss ESP95X, my desk and work area were better set up for closed headphones, though I loved the clarity and speed of stats. So I became curious if not obsessed with the earlier closed Koss stats. I bid on, but ultimately decided not to buy several versions of the ESP9. During the lockdown I decided I needed a new and more ambitious nerd project. So I bought a Koss ESP6 and decided to wire them to the male end of my Koss ESP extension cable. I ripped out most of the internals first, but left them closed with minimal damping. Sadly, being closed, they lost most of the stat character. Like they sounded originally through the standard headphone jack out of my amp - they still sounded congested and echoey.
I had read on another forum about someone that wired their Koss ESP9 for the Koss E90 amp, but they left the PCB. I decided to go one step further, and leave the drivers nearly completely exposed. The first attempt at making them open was disappointing. The two layers of felt over the drivers, and the plastic grills on the pad side were the culprit - when I removed them I was shocked at how good they sounded.
Now that I know they sound good I'm going to make or buy a better cable as opposed to my jerry-rigged mess, and create a nice grill. Overall the mids and treble sound clearer than my Koss ESP95X though the sound stage is more intimate. I have not tried them directly back to back, but I will eventually. I suspect a lot of people may be put off by the agressive treble. Sadly, they're still bass light even with my Stax SRM717 but I've been listening to them with a 3 decibel boost under 100Hz, and they sound fantastic to me.
I believe the Koss ESP6 were originally wired single ended. The black and yellow cables are connected to each stator. But is it possible I've inadvertently connected one side to ground and am damaging my amp? I'd appreciate any feedback on that.