XACT S1 EVO Music Server

A reference music server built around the world’s first audio-dedicated motherboard with 100% linear power delivery — the streaming source designed to make digital sound like analog without any of the limitations.

The S1 EVO is XACT Audio’s flagship music server, the second-generation refinement of an architecture that has redrawn what reviewers expect from a streaming source. Marcin Ostapowicz spent six years engineering it from a blank sheet — no off-the-shelf mini-PC motherboard, no switching power converters anywhere in the signal or power path, no compromises imported from the IT world. Every hardware decision was ear-tested against the question that defines XACT: does it bring the playback closer to the live performance, or does it not.

What you hold when you lift an S1 EVO is a fanless aluminum chassis carrying a custom motherboard that XACT bills as the world’s first 100% linear-powered audio motherboard. The OPTIMO X1 power section delivers 140,000 µF of Nichicon Muse flagship capacitance with linear regulators on every rail. Timing comes from a Master OCXO clock board developed in-house — oven-controlled for stability, mechanically isolated, with a dedicated linear supply of its own. Storage is a specially selected 4 TB SSD (8 TB available on request); the operating system, XACT OS, runs from a single-level-cell SD card chosen for its sonic signature and loaded with JPLAY playback software. Six gold-plated, EMI-shielded RJ-45 inputs with built-in 12-core transformers let the S1 EVO double as the audio-grade switch ahead of itself, with an LED-off feature on the LAN ports because even indicator LEDs are a noise source when the goal is this kind of silence.

The “EVO” suffix marks the upgrade path that Marcin took after living with the original S1 in his own system: the in-house Master OCXO clock, the IMMOTUS ceramic-aluminum isolation footers (developed in-house, also sold separately), and an upgraded internal music-drive cable carrying the same proprietary geometry as XACT’s Phantom USB and LAN cables. The result, in the audiophile press’s language, is a server that approaches analog playback from the digital side — purity and untarnished truth, in Jason Kennedy’s phrase, with a noise floor low enough that the music has somewhere to go.

Place an S1 EVO between your network and any high-end DAC over USB. It pairs naturally with the rest of the XACT family — the N1 Network Switch upstream, Phantom cabling, Immotus footers — but it will reward any well-resolved system feeding any serious USB DAC. JPLAY’s iOS app handles control, library, and streaming from Tidal and Qobuz, with native bit-perfect playback up to DSD512 and 768 kHz PCM. The S1 EVO is a flagship-class component — the audition is the conversation, and we are happy to set one up at either showroom.

“It delivers everything that is good about digital audio, apparently without any of the problems that afflict the format.”
— Jason Kennedy, Hi-Fi+, December 2025

“I have rarely heard such purity and untarnished truth.”
— Jason Kennedy, Hi-Fi+ issue 241

“A new high for streaming sound.”
— Jason Kennedy, The Ear (Editor’s Choice), 2025

“The finest digital transport I have experienced.”
— Joël Chevassus, 6moons

Main Features

01. World’s first 100% linear-powered audio motherboard. A fully custom motherboard developed from a blank sheet for music playback only — no switching converters anywhere on the board, no IT-grade compromises imported from general computing. The OPTIMO X1 power supply section delivers 140,000 µF of Nichicon Muse flagship capacitance with linear regulators across every rail.

02. Master OCXO clock board. Oven-controlled, in-house developed, mechanically isolated, fed from its own dedicated linear supply. Timing precision and stability at the level the rest of the architecture demands.

03. IMMOTUS mechanical isolation. Aerospace-grade aluminum and ceramic-ball-bearing footers, developed in-house, channeling internal vibrations away from the signal path. The same footers XACT sells separately for use under other components.

04. Phantom Music Drive Cable. Proprietary internal music-drive cabling sharing geometry and materials with XACT’s external Phantom USB and LAN cables — minimizing interference between storage and the audio output stage.

05. Six audio-grade Gigabit Ethernet inputs. Gold-plated, EMI-shielded RJ-45 connectors with 12-core isolation transformers; LED-off feature reduces in-chassis noise. The S1 EVO can serve as the audiophile switch ahead of itself when desired.

06. Two USB Audio 2.0 outputs. Main USB and a second USB output without 5 V power bus for DACs that prefer to supply their own. EMI-shielded, gold-plated, high-durability connectors throughout.

07. XACT OS and JPLAY playback. Custom operating system written from scratch for this hardware, loaded from an SLC SD card; JPLAY playback software with lifetime license; iOS control app; native Tidal and Qobuz integration; full local-library support up to DSD512 and 768 kHz PCM.

08. Specially selected 4 TB SSD. Audio-graded storage chosen for sonic signature, not specification-sheet specs. 8 TB capacity available on request.

Specifications

Function: Reference music server / streamer for high-end digital playback over USB

Motherboard: 100% custom, 100% linear-powered, audio-only (in-house developed)

Power supply: OPTIMO X1 linear power supply section, 140,000 µF capacitance (Nichicon Muse), linear regulation throughout

Master clock: OCXO clock board with dedicated linear supply, mechanically isolated

Mechanical isolation: IMMOTUS ceramic-aluminum footers (aerospace-grade aluminum, ceramic ball-bearing interface)

Internal cabling: PHANTOM Music Drive Cable (proprietary)

Storage: 4 TB SSD (8 TB on request); SLC SD card boot drive

Operating system: XACT OS (custom, written from scratch)

Playback software: JPLAY (lifetime license included)

Remote control: JPLAY iOS app

Streaming services: Tidal, Qobuz (native)

File support: DSD up to DSD512 (DSF, DFF); PCM up to 768 kHz, 16–32 bit (FLAC, ALAC, WAV, AIFF); MQA pass-through

Digital outputs: 2× USB Audio 2.0 (main + isolated, no 5 V power bus); gold-plated, EMI-shielded

Network inputs: 6× Gigabit Ethernet, gold-plated EMI-shielded RJ-45 with 12-core isolation transformers; LED-off feature

Chassis: Aluminum, fanless

Dimensions: 439 × 315 × 100 mm (W × D × H)

Weight: 10 kg

Designed by: Marcin Ostapowicz (founder of JPLAY and JCAT)

Designed and built in: Poland

For more information visit the dedicated S1 EVO page on xact.audio