Drop and Koss need to make these available terminated with a Stax Pro plug so they can be easily used with the majority of electrostatic amplifiers in existence. I soldered my own adapter and I'm using them with an old refurbished Stax SRM-1 Mk2 and they sound INCREDIBLE for the price. I had a purge of audio gear after buying Focal Utopias, but these are one of the few things that survived.