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The SPL Phonitor One is a stylish headphone amplifier that offers an audiophile-grade monitoring experience to home listeners and audio professionals alike.


Because of its two pristine Burr-Brown OPA2134 SoundPlus preamps, the unit is suitable for those who enjoy critical listening with extremely low noise and minimal distortion. The output stage is a push-pull Class AB amplifier with ample power to drive a wide range of popular headphone models, from consumer-grade, low-impedance headphones to audiophile high-impedance headphones.


Two audio sources—such as a DAC, CD player, mixer, or a tape machine—can be connected to the analog line inputs via the balanced 1/4" and unbalanced RCA connectors. An input selector lets you quickly switch between the two sources.
The Crossfeed knob engages the Phonitor Matrix, SPL's technology for emulating speaker positioning within a room, all in your headphones. With the Crossfeed knob, you can dial in subtle amounts of the opposing channel to emulate the acoustic signature of stereo speakers. Mixing engineers might find this feature particularly handy when mixing using headphones.


The Phonitor One comes with a 12V external power supply.

Comprehensive Preamp Stage

- Two Burr-Brown OPA2134 SoundPlus operational amplifiers provide the pre-amplification. These are specially designed for audiophile circuits and are characterized by low noise and minimal distortion of 0.00008%. Thanks to a true FET stage, the OPA2134 achieves a slew rate of 20V/µs, making it a high-speed operational amplifier. This has an immediate positive effect on the liveliness of the playback. Additionally, low capacitance film capacitors are installed in the signal path as bypass capacitors of the coupling capacitors, which ensures a more precise transmission of the high-frequency signal components. Finally, the Panasonic 'Electric Double Layer' gold electrolytic capacitors are used as coupling capacitors.

Class AB Power Amp

- The output stage of the headphone amplifier is designed as a push-pull amplifier in Class AB mode. The bipolar transistors share the amplification of the positive and negative half-waves, which produces a higher gain and a higher output voltage than in Class A operation, where only one transistor amplifies both half-waves.

The output stage transistors are thermally coupled and thus run particularly coherently, which contributes to a consistent and stable sound image. The power supply has a buffer circuit with low source resistance, ensuring generous current reserves even when operating low-impedance headphones.

Adjustable Crossfeed for Stereo Speaker Sound

The headphone amplifier features SPL's Phonitor Matrix with adjustable crossfeed, which enables you to use your headphones to create mixes that translate accurately when played on speakers. The Crossfeed knob determines the crosstalk of the channels, the so-called interaural level difference. The intensity of the crossfeed is fully variable.


At the beginning of the control path, the function is not in the audio path. It is only switched on by adding it via relay (hysteresis circuit). The audio signal therefore does not pass through the crossfeed stage if this is not desired.

Power Supply

The unit comes with a 12V plug-in power supply unit, which works in tandem with the secondary built-in power supply to generate a voltage level of +/-17V for the analog audio sections, achieving professional audio levels up to +22.5 dB.

SPL Phonitor One Audiophile Headphone Amplifier

  • SPL Phonitor One Audiophile Headphone Amplifier
  • The SPL Phonitor One is a stylish headphone amplifier that offers an audiophile-grade monitoring experience to home listeners and audio professionals alike.
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