Phonitor One d

The audiophile headphone amplifier

with innovative Phonitor Matrix, 32-bit DA-converter and outstanding sound quality.

Monitoring in highest sound quality with up to 32 bit and 768 kHz.
Create perfect mixes on headphones – thanks to the Phonitor Matrix.

number one in sound

For us the sound is always in the foreground. When it sounds good, we like to listen. To get such a sound, you need experience and technical finesse. We have incorporated both into the Series One.

The design of the amplification stages

The preamplifier stage

Two Burr-Brown OPA 2134 SoundPlus™ operational amplifiers provide the pre-amplification. These are specially designed for audiophile circuits and are characterized by extremely low noise and minimal distortion of only 0.00008%.
Thanks to a true FET stage, the OPA 2134 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.

In addition, 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.
The excellent Panasonic ‘Electric Double Layer’ gold electrolytic capacitors are used as coupling capacitors. They offer the highest storage capacity of all capacitor technologies

The headphone output stage

Weak sound on headphones?
Not enough power?

Not here. Phonitor One d delivers a full headphone sound – and that up to really loud.

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.  

The Revolution: Phonitor Matrix

The Phonitor Matrix is the revolution in the headphone amplifier.

It enables mixing and mastering engineers to create perfect mixes on headphones, which will translate perfectly to all types of stereo speaker systems.

With the Phonitor Matrix, you can create mixes on headphones that sound just like on speakers.

But the Phonitor Matrix is not only designed for professional use in the studio.
It also enables the hifi enthusiast to enjoy music on headphones, like if it was played back on speakers.

How is this possible?

Music is normally produced and mixed for playback on stereo speakers.

Listening on headphones is different from listening on loudspeakers. The biggest difference is the lack of crossing signals of the sound signal from the left speaker to the right ear and from the right speaker to the left ear.

These crossing signals are missing in conventional headphone listening, because there are no signals crossing from one side of the headphones to the other. This results in an unnaturally wide stereo stage and sound sources are not played back at their correct position in the stereo spectrum.

The SPL Phonitor Matrix can correct this false stereo image with an analog circuitry.

The Phonitor Matrix parameters

The two main parameters of the Phonitor Matrix are Crossfeed and Angle:

• Crossfeed determines the crossing signals of the channels.
• Angle determines the opening angle of the stereo image.

The “Crossfeed” parameter of the Phonitor One is continuously adjustable via the crossfeed control.
The “Angle” parameter is fixed at the studio standard of 30°.

To perfect the listening experience, the level of the sound sources centered in the stereo image must be attenuated when the Phonitor Matrix is activated. The result is that not only the position of all sound sources is correctly located, but also their volume. 

For the Phonitor One, this parameter, which we call “Center” for the Phonitor Matrix, is fixed at a -1 dB cut, which is the best choice for an authentic representation of the soundstage.

During conventional listening on headphones, our brain can compensate a certain level of false playback representation – but this is very exhausting and leads to listening fatigue.

Free choice – three stereo inputs 

The Phonitor One d offers two analog stereo inputs (TRS and RCA) and one digital (USB).

A computer, tablet or smartphone can preferably be connected via USB.

Input devices with an analog output signal, such as CD players, mixers, synthesizers or an analog tape machine/tape deck, can be connected balanced (TRS jacks) or unbalanced (RCA) at the analog line inputs. 

The best is just good enough – 32-bit DA-converter

Of course, no compromises were made with the converter chip either. For example, the Phonitor One d also uses the premium AK4490, 32-bit DAC with AKM’s Velvet Sound® – just like our bigger DACs.

This technology makes the finest details audible thanks to its low-distortion architecture.

It supports sampling frequencies up to 768 kHz PCM (16x CD resolution) and DSD (Direct Stream Digital) playback up to DSD4 or DSD256 (11.2 MHz) resolution.

The Phonitor One d automatically synchronizes to the sampling rate applied to the USB input. No further settings on the device are necessary.

A Great Connection

The USB connection is Class Compliant. This means that all Mac computers and iOS devices like iPads and iPhones can use the full performance of the DA-converter without driver installation.

iOS devices require the “Apple camera adapter”.

For Windows, a driver is only required if higher sampling rates are desired. The driver is available for download at the bottom of this page.

Line Out

Phonitor One d is not only a headphone amplifier but also a stand-alone DAC! The signal selected in the input section is output unchanged at the line output “Line Out”.

The line output has unity gain, which is a normal, unregulated output level – it is independent of the volume control for the headphone amplifier.

Thus, the Phonitor One d can also be used as a state-of-the-art DA-converter, which recommends it for a series of other tasks.

This signal can be routed to a monitor controller, for example.

Or multiple users can listen in via additional headphone amplifier (e.g. Phonitor One) connected to the Line Out.

The Phonitor One d can also be easily looped into a monitoring chain without the need for another output at the playback source.

But you can also record the signal analog or send it to a mixer for further processing.

There are no limits to creativity here.

Power Supply

Good sound always starts with the power supply. This is where you lay the foundation for the performance of the entire device. Although we “only” supply a 12 V plug-in power supply unit, the secondary power supply inside generates a voltage level of +/-17 Volts for the analog audio sections with which professional levels of up to +22.5 dB can be achieved!

An elaborate low-drop operating voltage regulation provides more “juice” and regulates cleanly even when the maximum operation voltage is reached.

The Phonitor One delivers full power when used with the included 1.5 A power supply.

Just switch it on and enjoy the great sound. The ON-switch puts the Phonitor One into operation.

Number One in Sound

With the Series One – just as with all other SPL devices – we develop not only according to plan, but also by ear from the very beginning.

Many important components are installed on the circuit boards using Through-hole technology. This way we can ensure that we can use the best sounding components.

For audiophiles, sound engineers, and music professionals seeking unparalleled headphone listening experiences, the SPL Audio Phonitor One d is a premium headphone amplifier and DAC designed to deliver exceptional clarity, precision, and comfort. Whether you are mixing tracks, mastering audio, or simply enjoying high-resolution music, this device provides the tools necessary to recreate a natural, speaker-like soundstage right through your headphones. The Phonitor One d addresses the common issue of listener fatigue and inaccurate stereo imaging that many headphone users face, making it indispensable for critical listening environments.

At the heart of the Phonitor One d is its unique crossfeed technology, which simulates the natural crosstalk between speakers in a room. This means you hear a more realistic stereo image with reduced ear fatigue, allowing for longer, more comfortable listening sessions without the harshness typically associated with headphone use. The adjustable speaker angle and center level controls further enhance this effect by letting you tailor the soundstage to your precise preferences, replicating the experience of listening to high-quality speakers in an acoustically optimized space. This level of control ensures that whether you are mixing or simply enjoying your favorite tracks, you experience sound as the artist intended.

Connectivity is another strong suit of the Phonitor One d. With two stereo analog inputs via 1/4″ TRS and dual RCA connectors, plus a stereo digital input via USB Type B, this amplifier integrates seamlessly with a range of audio sources from professional audio interfaces to consumer-level devices. The inclusion of a high-quality digital-to-analog converter allows for pristine digital audio playback, ensuring that your digital files are rendered with the utmost fidelity. The single stereo analog output and dedicated headphone output make it straightforward to connect studio monitors or headphones without signal degradation.

Designed as a compact desktop unit weighing just 3.2 pounds, the Phonitor One d fits comfortably into any professional or home studio setup without occupying excessive space. The included 12 V DC power supply ensures stable, reliable power delivery for consistent performance. All controls are intuitively laid out for easy adjustment during sessions, allowing you to focus on your work without distraction.

Practical applications of the Phonitor One d span from professional audio production to high-end personal listening. Sound engineers will appreciate the precision and natural spatial cues it delivers, enabling more accurate mixing decisions. Music producers benefit from the ability to fine-tune the soundstage and center level, ensuring mixes translate well across various playback systems. For audiophiles, the device dramatically enhances headphone listening, making long sessions enjoyable and revealing subtle details that are normally lost.

In summary, the SPL Audio Phonitor One d is a sophisticated headphone amplifier and DAC that elevates headphone listening to new levels of realism and comfort. Its innovative crossfeed technology combined with flexible input options and precise controls make it an essential tool for anyone serious about audio quality. Priced at ₹92,380, it represents a valuable investment in sonic accuracy and listening pleasure. With the Phonitor One d, you gain a reliable and expertly crafted audio solution that brings your music and mixes to life with clarity, depth, and true-to-life spatial imaging.