Home / SPL AUDIO Phonitor One d - Headphone Amplifier
Product Overview
The Premium Standard for High-Resolution Digital Reference Monitoring The SPL Phonitor One d is the upgraded digital-end version of the critically acclaimed Phonitor One architecture. It directly addresses the needs of modern recording engineers, content creators, and audiophiles who require a reference-class headphone amplifier alongside a flawless internal converter to bypass subpar computer soundcards. Built by hand in Germany using premium discrete components, its centerpiece is the analog crossfeed Phonitor Matrix. This circuit replicates the natural, three-dimensional crosstalk and spatial angles of a professional studio loudspeaker monitor setup, allowing you to make definitive panning, balancing, and EQ decisions without causing listening fatigue.
Product Description
Premium AKM Velvet Sound DAC Architecture: The digital core of the Phonitor One d features the highly celebrated AK4490 premium DAC chip from Asahi Kasei Microdevices, incorporating signature Velvet Sound™ technology. This high-resolution converter operates with 32-bit processing and handles pristine digital audio streams via class-compliant USB, supporting sampling frequencies up to 768 kHz PCM and native DSD4 (DSD256). The chip’s internal digital filters are meticulously optimized to minimize pre-ringing artifacts, ensuring an ultra-linear phase response and a jaw-droppingly transparent soundstage with zero digital harshness.
Bespoke Burr-Brown Preamp and XMOS Digital Interfacing: The digital USB input path is managed by a high-performance XMOS microcontroller, providing asynchronous, jitter-free data alignment directly from your Mac, PC, iOS, or Android host device. Once converted, the analog stage is driven by two premium Burr-Brown OPA 2134 SoundPlus™ operational amplifiers. These specialized chips use a low-noise FET input design to achieve a lightning-fast response speed of 20V/µs and an incredibly low distortion rating of just 0.00008%, ensuring that every micro-detail of your track's transients remains perfectly preserved.
Powerful Class AB Power Amplifier Stage: The headphone power amplifier runs a high-output push-pull design operating in Class AB mode. Utilizing thermally coupled bipolar transistors to divide the positive and negative cycles of the audio waveform smoothly, the circuit outputs exceptional current and voltage reserves. A low-resistance output design allows the Phonitor One d to comfortably handle any pair of headphones on the market—whether driving high-impedance 600-Ohm audiophile models to maximum volume or keeping background hiss non-existent on ultra-sensitive, low-impedance in-ear monitors (IEMs).
The Revolutionary Phonitor Matrix (Adjustable Crossfeed): Traditional headphone listening creates an artificial, exaggerated left/right stereo split that doesn't exist in the real world. The Phonitor One d solves this via its variable Crossfeed control knob. The unit emulates an industry-standard studio configuration, pre-setting a 30° speaker placement angle and a -1 dB center level reduction. By adjusting the knob, you control how much of the opposite channel's signal bleeds into each ear, mimicking interaural level and time differences. Turning the knob to "Off" engages an internal hysteresis relay that mechanically bypasses the matrix entirely, providing an untouched, pure-analog line path.
Dual Rails and Comprehensive I/O Switching: The rear panel provides excellent integration options for both pro-studio and high-end consumer hardware. It features balanced 1/4-inch TRS line inputs (+4 dBu), unbalanced RCA stereo inputs, and a Class-Compliant USB-B digital input. A dedicated front-panel three-way switch toggles seamlessly between these sources. To top it off, while the device utilizes an external 12V DC power supply, its internal secondary power supply converts and boosts this voltage up to a staggering ±17 Volts for the analog audio sections, giving you massive dynamic headroom and professional line level handling up to +22.5 dBu.
Key Features
Integrated 32-Bit/768kHz AKM DAC: Premium AK4490 Velvet Sound™ converter chip handles ultra-high-resolution PCM and native DSD256 digital formats.
Innovative Phonitor Matrix: Analogue speaker-emulation crossfeed mimics stereo monitor crosstalk to ensure headphone mixes translate accurately onto standard PA and hi-fi systems.
Continuously Variable Crossfeed: Front panel knob scales the spatial crosstalk effect, engaging a true internal hardware relay to maintain a pure signal when turned to "Off."
Burr-Brown OPA 2134 Op-Amps: High-fidelity preamplification infrastructure yields an articulate, transparent tone with a near-zero distortion floor.
High-Current Class AB Topology: Powerful push-pull output stage utilizing paired bipolar transistors ensures steady, uncolored amplification across all headphone impedances.
High-Voltage ±17V Internal Rails: Internally steps up incoming voltage to generate professional headroom, preventing distortion on loud audio peaks.
Tri-Source Switching (USB, TRS, RCA): Front-panel toggle switch switches fluidly between digital computer connections, balanced studio hardware (+4 dBu), and consumer RCA gear.
Technical Specifications
Feature
Specification
Device Type
Analog Desktop Headphone Amplifier with Integrated 32-Bit DAC
Digital Converter Chip
AKM AK4490 Velvet Sound™ Architecture
Supported Digital Formats
PCM up to 768 kHz (32-bit) / Native DSD up to DSD256 (DSD4)
Digital Interfacing
Asynchronous USB 2.0 (Type-B), Class-Compliant (No drivers needed for macOS/iOS)
Analog Inputs
2 x 1/4" TRS Balanced (Line 2) / 1 x Dual RCA Stereo Unbalanced (Line 1)
Headphone Output
1 x 1/4" (6.35 mm) TRS Stereophonic Jack
Output Source Impedance
20 Ohms
Frequency Range
10 Hz to 200 kHz (-3 dB, Analog Section)
Maximum Output Power
2 x 190mW @ 600Ω / 2 x 330mW @ 250Ω / 2 x 400mW @ 47Ω
