Up for sale is a rare classic when it comes to electrostatic headphones. Made between 1975-1979, these headphones still outperform some of the best conventional high end headphones of today. I am selling with two models of energizers. The SRD-7 and the SRD-6. All units are in good working order. Cosmetically in excellent condition. The ear pads are worn, but unbelievably, Stax sell replacements for $25. My personal experience with these headphones has always been wow, I can't believe how good these sound! Incredibly neutral and open. I know you'll agree!