SMSL SU-1 Review: Clean Conversion and the Pops Between Tracks

Twelve firsthand writers distinguish the SU-1's clean measured conversion from conflicting reports about USB switching pops, audible differences and an individual hardware failure.

Article date October 11, 2026Drew Wiberg / Recluse Studio5 semantic kinds

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Scope note: This literature review concerns the SMSL SU-1 desktop DAC, using twelve distinct writers’ original measurements and actual-use write-ups. USB, optical and coaxial operation remain separate where the sources separate them. The article attributes each listening comparison, fault and troubleshooting step to its writer; Drew has not performed the equipment tests described here.

The SU-1 can convert a playing signal cleanly and still produce an unwanted sound when playback starts or its sample rate changes. Published accounts describe both. The distinction matters because measurements taken during steady playback do not automatically establish quiet transitions between tracks.

Twelve firsthand records support good conversion in several systems. Their disagreements concern the size of audible differences, the circumstances that produce pops, and an individual failure. Those disagreements give this small DAC a more useful review than either a measurement score alone or a collection of listening adjectives.

An available USD offer, with power kept in the description

The catalog ID is f719600a960315b88c60. On 11 October 2026, HiFiGo’s new SU-1 offer displayed $79.99 USD and Add to cart. The retailer’s live product data marked the SU-1 variant available, and its store currency was USD. That is the item price before checkout charges; no currency conversion is needed.

SMSL’s specification identifies an AK4493S converter, XMOS XU-316 USB interface and USB power. The SU-1 accepts USB, optical and coaxial digital inputs and provides stereo RCA analog output. A USB power connection is still required when optical or coaxial carries the audio. Its plain source button selects an input; this is a converter to feed an amplifier or active speakers.

The source window runs from April 2023 to July 2026. One bench review and two substantial editorial accounts sit alongside nine shorter owner write-ups. Separate authors in the same forum or Reddit discussion count separately, while repeated quotations and follow-ups do not add records. The sample is self-selected and does not establish how frequently a fault occurs.

Amir’s sample was arranged through ShenzhenAudio from SMSL. Headfonics’ Meldrick disclosed a ShenzhenAudio/SMSL sample and stated that the article used no affiliate links. vAudio Architect’s writer, signing G, disclosed purchasing the unit directly while maintaining a commercial relationship with SMSL. The installer context belongs beside that review’s observations. The owner posts do not establish financial affiliations.

The measurement result is unusually clear

Amir’s original ASR review measured very low noise and distortion, essentially flat audible-band response and strong linearity. Those measurements support accurate conversion under the stated test conditions. They do not measure years of ownership or every combination of computer, driver and playback software.

Meldrick at Headfonics listened through a Topping L30 II and Modhouse Argon MK3 headphones, comparing the SU-1 with an iFi ZEN DAC V1 used as a source for the same amplifier. Meldrick preferred the SU-1’s more neutral presentation in that arrangement. The account contributes an actual listening comparison, though its published method does not establish a blind, precisely level-matched result.

The reported comparisons become less uniform outside those reviews. DearSX at ASR reported little audible difference from more expensive DACs and sold them. In the same discussion, Herbert initially suspected a defective SU-1 after hearing artifacts, then found them in the recording itself. Herbert’s further comparisons included unequal output levels. The source can explain an owner’s revised diagnosis without establishing a universal sound signature.

Owners disagree about the size of the improvement

In a Budget Audiophile discussion, soundspotter connected the SU-1 between a PC and an Emotiva BasX A2m feeding Wharfedale Diamond 225 speakers. The writer first described a small difference, then a stronger improvement after further listening. qbert233 reported clearer, fuller playback through an iFi ZEN CAN and Hifiman Sundara than from a Realtek source. Choice_Student4910 described using a WiiM Mini and Sony CD player’s coaxial output with the SU-1, preferring its presentation to the Mini’s analog output.

The three accounts establish actual comparisons and favorable judgments, though their methods do not establish matched output levels or concealed device identities, and the starting converters differ between systems, so the reports cannot measure one common change. A replacement for a noisy or unsuitable analog output can help a particular system; these posts cannot show that every listener will hear the same improvement from every functioning converter.

The useful common ground is narrower: the SU-1 worked as the digital-to-analog connection in those owners’ systems. The reported size of the change remains a listening judgment, attached to each writer and comparison source.

USB pops have several documented conditions

G at vAudio Architect heard switching pops and noise in a mini-PC USB system feeding Yamaha HS8 speakers through a Palmer Monicon. Changing to separate power and a WiiM Pro digital connection removed the problem in that arrangement. Because both power and signal path changed, the result does not isolate USB power as the cause. G also reported satisfactory conversion in a larger speaker system.

Shadow12347 at ASR configured the first of four purchased SU-1 units for a virtual-machine audio setup feeding a Motu 16A. The writer heard pops around idle periods and playback starts, tried different rates and drivers, and reported that substitute interfaces did not behave the same way. Only the first SU-1 had been tested when that account was written; four purchased devices do not constitute four confirmed faults.

hammersjay reported that pops seemed resolved after several Raspberry Pi/Moode configuration changes. The combined changes prevent one confirmed remedy from being extracted. By contrast, LtMandella reported a month of frequent USB and optical use through JRiver, an A07 and Reference 3A speakers without a pop, mostly using optical.

These records support a transition problem in specific setups alongside successful operation in another. Neither a blanket claim that every SU-1 pops nor a blanket claim that a software switch cures the problem follows from them.

A failure report needs its troubleshooting attached

Firulais71’s July 2026 ASR write-up describes low output and severe distortion after roughly three months of normal operation. The owner changed USB cables, ports and computers, tried optical with different USB power supplies, and changed amplifier inputs. A separate CD player worked through the amplifier; the RCA leads had not yet been substituted at the recorded boundary.

That is substantial troubleshooting, with a remaining variable. It supports a failure in that owner’s playback chain strongly associated with the DAC, while leaving the internal failed part unconfirmed. Suggestions elsewhere in the thread about a particular internal power component remain proposed diagnoses, not the owner’s measured finding.

The positive listening accounts do not erase that fault. The fault does not supply a product-wide failure rate. Keeping both distinctions visible preserves what each source actually establishes.

The next test should include silence between signals

An unperformed controlled comparison would level-match RCA outputs, conceal the active converter, keep the recording and downstream system fixed, and separate steady playback from start, stop and sample-rate transitions. USB data with computer power, optical with separate USB power, and coaxial with separate USB power would require their own runs. Captured output would help distinguish a repeatable transition from a listening impression.

The narrow conclusion is that the SU-1 has strong measured conversion and documented success as an inexpensive digital input for several systems. Its published record also justifies checking transitions in the intended setup. A useful conversion result includes the track and the transitions around it.

The twelve firsthand records

All original sources were inspected on 11 October 2026. Each numbered record represents a distinct writer; the three Reddit reports have named author locators within one original discussion.