For sale as new & unmarked Cosonance Cyber 20b valve headphone amplifier £200 includes a free pair of Beyer DT990/600ohm headphones. The Consonance Headphone amplifier uses a pair of EL84 output valves connected as a triode with no overall global feedback coupled to the headphones using an output transformer, there are two headphone inputs plus a switch for selecting high or low impeadance headphones, original boxes for both are included.