Matrix Audio SU-1 USB Isolation Switcher

If you stream music to a USB DAC from a computer, phone, or tablet, there is a problem you may not know you have. The USB cable does not just carry audio data — it carries electrical noise from the source device, and it creates an electrical connection between your computer's ground and your DAC's ground. That connection is a highway for interference. Hum, grain, a closed-in quality to the soundstage — these are often ground noise in disguise. The SU-1 solves this by cutting that connection entirely, while also giving you the convenience of switching between multiple sources and multiple DACs without unplugging anything.

It is a small box. What it does to a USB audio system is not small.

Full galvanic isolation — what it means and why it matters

Galvanic isolation means there is no direct electrical connection between the input and output sides of the SU-1. Data, power, and ground are all separated by a dedicated professional-grade digital isolation chip. Your computer's ground and your DAC's ground are physically broken from each other. Ground loop noise — the kind that causes hum and muddiness — has no path into your audio system. High-frequency interference from switching power supplies and USB controllers cannot travel through to the DAC. Neither can power surges or lightning strikes.

What remains is the audio data, retimed and regenerated cleanly on the output side, with a quieter electrical environment for the DAC to work in. The background becomes darker. Details that were sitting just below the noise floor become audible. The presentation opens up. This is not a subtle effect in a resolving system.

Three inputs, two outputs, one button

The SU-1 has three USB inputs — two Type B for computers and dedicated streamers, one Type C for phones, tablets, or newer laptops — and two isolated USB Type A outputs for DACs or digital interfaces. Everything stays connected. Switching between sources is a short press of the front panel button, which cycles through the three inputs. A long press switches between the two outputs. The LED indicators show the active input and output at a glance. No menus, no software, no unplugging cables.

For a desktop system where a computer and a phone both need to reach a DAC, or where two DACs are available and you want to switch between them, the SU-1 handles the routing without compromising the isolation on any path.

The power supply

A fully potted toroidal transformer — sealed in epoxy resin for mechanical stability and electromagnetic shielding — feeds multiple ultra-low-noise linear regulators. Each USB output receives 5V at up to 1000mA from this supply, which is a meaningfully cleaner power source than a USB port on a computer or a switching wall adapter. The DAC draws its bus power from this regulated linear supply rather than from the noise floor of whatever is upstream. Real-time overcurrent and short-circuit detection cuts the output instantly if a fault occurs, protecting downstream equipment. The affected port's LED flashes red to indicate the condition.

Signal integrity over long runs

USB transmission impedance is optimised throughout the SU-1, which supports cable runs of up to 4 metres on each side — 8 metres total between source and DAC. Standard USB suffers signal degradation beyond a few metres; the SU-1's repeater circuit regenerates the signal at the output stage, maintaining data integrity without packet loss regardless of cable length. Your source and DAC do not need to be adjacent, which matters for desktop systems where cable routing is constrained and for living room setups where the streamer and DAC may be across the room from each other.

Where it fits

The SU-1 belongs in any system where USB is the connection between a digital source and a DAC, and where the listener suspects — or knows — that the system is not as quiet or as open as it should be. It is the correct first step before spending more money on the DAC or the source, because if the USB path is introducing noise, no amount of upstream or downstream investment fully corrects it.

Within the Matrix Audio ecosystem it pairs naturally with the NT-1, TT-1, ND-1, and TS-1. Outside it, it works with any USB audio device — computers, streamers, phones, and tablets on the input side; any USB DAC or digital interface on the output side.

Press recognition

The SU-1 is a recent addition to the Matrix Audio lineup. We will update this page as reviews are published.

Specifications

• Type: USB isolation switcher with linear power supply
• Isolation: Full galvanic isolation between all input and output ports — data, power, and ground lines separated
• Input ports: 2 x USB Type B (480 Mbps High-Speed); 1 x USB Type C (480 Mbps High-Speed); input power requirement under 5V / 100mA per port
• Output ports: 2 x USB Type A (480 Mbps High-Speed); maximum output power 5V / 1000mA per port
• Switching: Short press — cycles through 3 inputs; long press — cycles between 2 outputs
• LED indicators: 3 input indicators, 2 output indicators; red flash indicates overcurrent fault
• Power supply: Fully potted toroidal transformer; multiple ultra-low-noise linear regulators
• Overcurrent protection: Automatic output cutoff above 1000mA; restores on power cycle after fault resolved
• USB signal repeater: Optimised transmission impedance; supports up to 4m per side, 8m total cable run
• Power consumption: Under 15W
• AC input: 100–120V or 220–240V, 50/60Hz (factory fixed)
• Chassis: Full CNC-machined aluminium alloy
• Dimensions: 120mm W x 205mm D x 44mm H
• Weight: 1.58kg
• Manufactured: China

If you want to talk through whether the SU-1 solves the specific problem in your system — source noise, ground loops, multi-device routing — we are happy to work through it. Call us or start a conversation on the site.