The SPL HPm 500-Series Headphone Amplifier brings the Phonitor Matrix into the world of 500 series rack modules. Each of the two headphone outputs is fed with a separate amplifier to allow independent operation of two headphones with high-quality amplification.
 
With the Phonitor Matrix you control Crossfeed, Speaker Angle and Center Level to create speaker-like listenig and monitoring on headphones. The HPm can easily be inserted between the DAW and a monitor controller because the input signals of the HPm are slaved through to the outputs of the 500 series rack. Phase Inversion of left or right channel as well as a Stereo/Mono/Mute switch round off the feature set of the HPm.