With the Headphone Monitoring Amp HPm the SPL Phonitor Matrix is making headway 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. The Phonitor Matrix - derived from the High End Headphone Amplifier 'Phonitor' - eliminates the super-stereo-effect inherent in traditional headphone amplifier designs. In cases where speaker monitoring is impossible or just as an alternative thereto the Phonitor Matrix allows a speaker-like listening experience on headphones. With the Phonitor Matrix you create better mixes on headphones. Both the Crossfeed and Speaker Angle can be individually adjusted to achieve a headphone playback sounding equal to your loudspeaker playback. The adjustable Center Level supports the mix engineer to correctly level the phantom center signals when mixing 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.