·Review Basic Information

·Author: Yu Mengqi (also known as Monkey Yu)

Yu Mengqi (also known as Monkey Yu) has carved out a unique position in the field of audio review in China, thanks to his deep understanding of audio technology, genuine passion for music culture, and his distinctive hands-on style paired with a balanced perspective. His talkshow not only provides reliable equipment insights for audiophiles, but also opens a window to music appreciation and lifestyle aesthetics for general listeners. As the host, Mr. Yu's personal journey from "tinkering with gear" to "returning to the music" reflects a common path for many enthusiasts, making the show's content more resonant and valuable as a reference.

USB Isolation + Devices Switching

Hands-On with the Matrix Audio SU-1

There are certain devices that, when you first get them, you don't think you need them. Then you start creating needs for yourself and spending more money — or, thanks to that device, you suddenly unlock use cases and system configurations that were previously impossible. The Matrix Audio SU-1 is exactly that kind of device for me.

First of all, the SU-1 differs from the earlier SI-1 in architecture. Instead of the optical isolation approach used before, it features a dedicated chip-based solution for USB signal isolation. USB isolation products have actually been around for years —I experimented with some over a decade ago, and even Schiit Audio in the US released something similar back in the day.

But compared to those older USB isolators, Matrix Audio wanted to add a little more functionality — like multiple inputs and outputs. So the SU-1 ended up with two outputs and three inputs. On the input side, you get two USB-B ports and one USB-C port. On the output side, two USB-A ports. A single button on the front panel lets you switch between inputs (short press) and outputs (long press).

Important note: the multiple inputs and outputs cannot work simultaneously — this is a selector, not a USB hub.

Personally, I wish one of the outputs were USB-C, but considering this is a 220V mains-powered device designed for desktop use, dual Type-A makes sense. When Matrix Audio first told me about this product, I understood the isolation need — plenty of audiophiles face that. But the multi-device switching part threw me off at first. Who has two USB DACs? And three computers?

Then I realized the multi-device switching is essentially a bonus feature. If you imagine its primary use case — say, between a network bridge and a USB DAC — one input and one output is all you really need. But if you also have other "less critical" audio devices in daily use, the SU-1 can still benefit them.

One key point Matrix Audio emphasizes is better impedance matching, supporting up to 8 meters of total cable length — meaning 4 meters maximum on each side, with the SU-1 sitting in the middle. So if your computer is connected to a USB all-in-one, audio interface, or powered speakers with USB input, you can route that everyday audio chain through the SU-1 for isolation and improved sound quality. The SU-1 also delivers 5V/1A output power, so standard USB-powered audio devices like audio interfaces and compact all-in-ones can run directly off it.

Back to my earlier point — since my main DAC runs Roon Ready natively, I didn't initially have a USB need. So I questioned whether I even needed the SU-1, and how I would use it. Eventually, I found it solved a long-standing pain point: I have two computers in my study.

With the SU-1, I connected my SSL2 audio interface to it, so both computers can share the interface simply by switching inputs — whether for recording or driving a pair of powered monitors, it became much more convenient. Meanwhile, the second output goes to my DAC's USB input. While I don't use that often, it's handy when I want to play audio from my computer or access Apple Music directly.

Sound-wise, this isn't my first encounter with USB isolation. I've tried several units before, but most of them only handled signal isolation — either lacking power delivery altogether or offering no power enhancement. Matrix Audio, however, enhanced the power delivery on the output USB port, which made me curious.

I tested the SU-1 with three devices: the Topping DX3, SSL2 MK2, and FiiO WARMER tube DAC. Notably, the first two are USB-powered — I wanted to see if the SU-1's power delivery was up to snuff. My hunch was that USB-powered devices might show more noticeable improvements, since Matrix Audio states the SU-1's USB output power section is isolated from the input and uses a toroidal transformer-based linear power supply design.

The results: improvements were audible across the board. And generally, the worse your upstream source, the bigger the improvement. My Windows PC, for instance, has zero Hi-Fi optimization — it's basically a gaming machine — so the improvement after isolation was the most dramatic. Both the USB-powered devices and the externally powered FiiO DAC showed clear gains. The sonic character shift was similar to what I heard with the SI-1: a blacker background, more defined micro-details across the frequency range. Compared to the SI-1, which mainly affected the low end, the SU-1 adds some extra lift to the treble, improving transparency noticeably.

For USB-powered devices, the effect was even more pronounced. Interestingly, USB-powered gear sounds slightly different depending on whether it's connected to a Mac, a Windows PC, or through a dock. After going through the SU-1, those differences were reduced — not entirely eliminated, since the system and dock themselves still exert influence — but significantly narrowed.

Thanks to the SU-1, I even swapped my keyboard for Topping's recently released KB22 audio interface keyboard — freeing up another slot on my desk. Now, whichever computer I'm using, I just switch the SU-1's input to the corresponding port, and both computers share the same audio interface and keyboard. The KB22 is interesting in its own right — maybe I'll do a dedicated episode on it sometime. With the SU-1, my current setup uses two inputs for my two computers, and two outputs: one for the Topping KB22 keyboard, the other for my Yulong D39 DAC.

In the end, after using the SU-1 for two or three weeks, I've come to understand my initial confusion. You might think: a 3-input, 2-output device when you only need 1-in, 1-out — so part of what you paid for feels wasted. I think that's a common reaction, and it's fair. But after living with it, I see it differently. Those extra inputs and outputs aren't redundancy — they're possibility. They give you flexibility and room to experiment. That's the kind of redundancy that's worth having.