SMSL SU-1 – The DAC That Breaks the Rules!

SMSL SU-1 is a truly affordable DAC at $79, but if such a low price makes you skip this review and go read about something pricier – you will miss out on something truly special.

Build and Features

SU-1 is a small and simple-looking DAC, yet SMSL has decided to use aluminium instead of plastic which makes it positively firm and sturdy. In the back, you’ll find three digital inputs: USB-C, optical, and coaxial. USB-C is at the same time the one that powers the device, and if you use it for the audio signal, your PC will power the whole device too. On the other hand, when you use an optical or coaxial connection for an audio signal, USB-C has to be connected to the 5V power supply which is not provided in the box. SMSL SU-1 has a very low power consumption so literally any 5V power brick will do, including small phone chargers. Next to those three inputs, you can find a set of RCA outputs. Those are fixed in level and single-ended.

In the front, things are even more simple. There’s just one button that powers the unit. There is no automatic signal detection or sleep function, so the DAC is either ON or OFF and you put it in those states manually. That same button is also used to circle the inputs when pressed shortly. Several LEDs will let you know which input is selected, and one LED is dedicated to tell you if an MQA signal is detected. Yes folks, this small and simple $79 DAC supports MQA hardware encoding. Make of this what you will, I simply find it interesting.

The whole DAC is based around the Asahi Kasei’s AK4493s DAC chip. Powerful XMOS XU-316 will accept the USB signal and provide high resolution for both PCM (up to 768 kHz, 32 bit) and DSD (up to DSD512). You couldn’t ask more even from the high-end D/A converter.

So SMSL SU-1 is simply a DAC without volume control, headphone amplifier, fancy display, etc. But how does it sound? Well, let’s find out.

Sound

SMSL SU-1 sounds amazing. It’s very revealing and with well-balanced tonality. The bassline is deep and punchy, there’s a real vigor there that I’ve never before heard at this price point. But it doesn’t end with the bassline, move up the frequency spectrum and everything keeps sounding lively and engaging. String plucks have energy, cymbals have sparkle, and drums have kick and weight. This small DAC creates a very engaging sound indeed. I move to something slower that requires refinement too, like some of my favorite Jazz or Country singers, and SU-1 presents me with full and present vocals. They have good tone timbre and plenty of inner details too. Simply put, no part of the sound is left unattended. It doesn’t matter if you prefer fast-paced electronica or low-key country, this DAC will have you covered with great detail retrieval, natural tone, and great dynamics.

Moving to the soundstage SU-1 is competent. Instruments are well separated, and there is a good sensation of air around them. It’s not that it can develop a wide and deep soundstage that DACs nearing one thousand dollars or euros can spread, but it will not embarrass itself either. Put it against any Delta Sigma DAC up to 500 dollars and I dare you to say SU-1 sounds congested next to them.

The more I listened to this DAC, the more I asked myself if it was really that good or am I just having a good day. You probably know those days when everything sounds good to you. I had to put it to a few head-to-head comparisons to find out.

Comparisons

Topping E30 II goes for twice the price but it comes with a remote and volume control function. If that’s something you need it trumps the SU-1 regarding features. In case you don’t care about that but only about the sound quality, it gets more interesting. Both have comparable levels of detail retrieval and great dynamics, but their tonality is different. Topping E30 II is a warmer and darker-sounding DAC. It offers a fuller bassline but tamer, or darker, highs. SMSL SU-1 is a bit more open and more airy. One can fit better in your system depending on the rest of the components, or simply suit your taste more. But objectively speaking these two are on the same level sonic-wise. That statement is actually quite important because E30 II brought fantastic value to the market itself, bringing the overall clarity, full tonality, and good dynamics that I never previously heard below ~$250. Now SMSL just upped the game by bringing that same audio quality below one hundred.

Because of this, comparison to any earlier DAC like SMSL SU-6 or C200 makes no sense, SU-1 is simply better. To meaningfully surpass it you would have to go to the likes of SMSL SU-9 pro or Topping E70 velvet. Even then, it’s quite a modest difference, not a night and day one one might expect from the models that are five times the price. And this leads me to the conclusion.

Conclusion

SMSL is known to make fantastic value products, but this time they still managed to overdo themselves. SU-1 can easily stand against two or three-times pricier models and equal them in terms of sound fidelity. If you’re on a limited budget and don’t need a feature-rich device, ignoring the SMSL SU-1 would be a huge mistake. Fantastic product at a fantastic price!

SMSL SU-1 – CHARACTERISTICS

Input: USB / Optical / Coaxial Output Level: 2.0Vrms Output Impedance: 47Ω THD+N: 0.00013% (-117dB) Dynamic Range: 121dB SNR: 121dB USB Transmission: Asynchronous transmission USB Compatibility: Windows 7/8/8.1/10/11，Mac OS X10.6 Above，Linux Bit Depth: USB:1bit~32bit, Optical/coaxial:6bit~24bit, Sampling Rate: USB: PCM 44.1kHz~768kHz, DSD  2.8224~22. 5792MHz Optical/Coaxial: 44.1kHz~192kHz MQA: 384kHz Power Consumption: <5W Standby Power: <0.1W Size: 96×27×78mm（W×H×D） Weight: 195g/0.43lbs