The E90 and E90x Electrostatic Energizer for the Koss ESP/950 and ESP/95X Electrostatic Headphones has separate Left Channel and Right Channel volume controls. Rotating the volume dials clockwise increases the volume. Rotating the volume dials counterclockwise decreases the volume. Both Left Channel and Right Channel volume dials work independently. Watch below to learn how to adjust the acoustic levels on your Koss ESP/950 or ESP/95X Electrostatic Headphones.