Phonitor XE

The SPL Phonitor XE is a headphone amplifier with Phonitor Matrix, remote volume control, a retro-style VU meter and optional DAC768 premium digital-to-analogue conversion. It uses SPL VOLTAiR technology throughout its audio circuitry.

Headphones can be connected through the standard stereo jack socket or the balanced 4-pin XLR output. The amplifier provides high output power for driving headphones, while the VOLTAiR circuit design supports detailed and dynamic audio reproduction.

Headphone outputs are provided on both the front and rear panels. A front-panel F/R switch selects between the front and rear outputs, allowing headphones to remain connected at the back without a cable across the front of the unit.

The 45 mm volume control is milled from aluminium and drives a motorised Alps RK27 “Big Blue” potentiometer. A red marker LED keeps the volume setting visible in low light. The volume can also be operated from any infrared remote control. The Phonitor XE learns the remote control command at the press of a button.

Up to 6 stereo sources can be connected. Analogue inputs are provided through XLR and RCA connectors. With the optional DAC768 installed, the available digital inputs are USB, coaxial, optical and AES. The Phonitor XE accepts balanced XLR and unbalanced RCA connections.

The DAC768 adds 4 digital sources and automatically detects the sampling rate and resolution of the connected source, whether that is a streamer, computer or CD player. No further settings on the amplifier are required.

The DAC768 uses an AKM AK4490 Velvet Sound™ DAC chip. It supports PCM audio up to 32-bit resolution and 768 kHz sampling rate, equivalent to 16 times CD resolution. Direct Stream Digital is supported up to DSD4, also known as DSD256.

Unlike the DAC 768xs, the DAC768 includes an AES/EBU digital input and the SPL DLP120 circuit with VOLTAiR technology.

The DAC chip’s analogue output is filtered by the DLP120 Dual Low-Pass circuit. It uses separate low-pass filters for PCM and DSD audio because the 2 formats require different roll-off frequencies. The filters use VOLTAiR technology to provide additional dynamic range, headroom and audio performance.

For the Professional Fidelity series, SPL develops circuits through both technical design and listening evaluation. Many components are mounted on the circuit boards using through-hole technology, allowing SPL to select the components used in the circuit design.

SPL’s 120V reference circuit operates at a DC voltage of 120 volts, 4 times the voltage used by IC-based semiconductor operational amplifiers. Within the Professional Fidelity series, this circuit is called VOLTAiR technology. The audio operating voltage is used to process the audio signal and is separate from the local mains voltage.

The 120V circuit operates at +/-60 V. SPL developed proprietary SPL 120V SUPRA operational amplifiers to handle this voltage. Conventional components and operational amplifiers would be damaged by it.

The high operating voltage supports the amplifier’s dynamic range, signal-to-noise ratio and headroom, as well as detailed audio reproduction and relaxed listening. The mains voltage from the power socket is converted inside the unit by a linear power supply with a toroidal transformer. Rectifiers then convert the transformer’s AC output into the DC voltage required by the audio circuitry.