I have an aftermarket cable which I had purchased to my Senns HD650 long ago. The HD650 were sold a while back but I still have the cable.
Is it possible to change the termination on this cable to fit my LCD-3?
it is. check the diy forum for more info on how to do it. you might need soldering gear. cable makers may not be interested as it's not profitable (money talks). someone in the diy forum might do it for a small fee or even for free, I would guess.