For Sale: Stax high-end electrostatic headphones and 6-tube amplifier. This set includes: SR-404 Signature electrostatic headphones [next to the top of the line Omega II's], 6T six tube amplifier. Frequency response DC to 42,000 cycles. Perfect for the higher demands of SACD and DVD-A audio CD's. Used less than 4 hours. Price including converter and Stax audio interconnect cables: $799.