The PHDA02 Reference Class Headphone Amplifier from Palmer can be used in stereo, mono, and dual-mono operation modes. While in stereo mode, the input signal is fed to the left and right earphones and the volume is set by the Stereo/Left control. In mono mode, the left and right channels are summed and the resulting mono signal is fed to both the right and left earphones. In dual-mono mode the left and right channels can be used independently, with individual level controls for the left and right earphones.
The Reference Class Headphone Amplifier operates with all headphones with an impedance of 8 to 200 Ohms. The front-panel inputs provide simultaneous connection of two parallel headphones. Impedance matching is achieved by a specially designed switchable transformer to provide superior performance, dynamic range and signal-to-noise ratio for all loads. Combo input sockets allow for balanced XLR and unbalanced TS headphone connection, while parallel XLR outputs facilitate daisy chaining multiple units. The amplifier is equipped with low-noise op amps and the output amplifier's discrete power transistors are mounted on heatsinks.