With 4 channels for audio monitoring and 4 sets of independent volume knobs and mute switches, you can get your group-on with the Zoom ZHA-4 4 Channel Headphone Amplifier.
Designed for the bands and multi-person podcasters of the world, this amplifier provides flexible mixing and easy portability.
The Zoom ZHA-4 weighs a mere 180g and is battery powered so you can easily mix your audio on the go.