By aspect — in detail
Transparency
Strong consensus · 9 srcThe strongest agreement in the set, and the entire point of the product. Audio Science Review's bench test lands it in the site's "excellent" DAC category, with full transparency achieved for distortion and noise, non-existent IMD, near-perfect linearity and a response that is essentially flat across the audible band; the SINAD figure quoted in the thread is 116 dB. Every listening source agrees the box has no character to speak of: Headfonics calls the timbre clean and neutral to the point that some would find it clinical, MOONSTAR calls the coloration very low, and an owner who switched between the SU-1 and a 30-year-old $2,500 TEAC CD player mid-disc could not hear a difference either way — with speakers or with electrostatic headphones. The one dissenting shade comes from Head-Fi's reviewer, who hears "a little bit of AKM's flavour"; no measurement supports a flavour, and no other source reports one.
“Full transparency is achieved not only for distortion but also noise”
amirm, Audio Science Review
“The SU-1 has a clean and neutral timbre that does not color the overall tonal balance at all”
Meldrick, Headfonics
“I was not able to hear any differences between the the CD player's DAC and the SU-1 DAC.”
Mark Rehorst
“One more on the pile of evidence that DACs are a solved problem.”
Blumlein 88, Audio Science Review
Measured
ASR's dashboard places the SU-1 in the site's "excellent" category of DACs; Amir reports full transparency for both distortion and noise, IMD limited by noise alone, negligible jitter spikes, almost perfect linearity and an essentially flat in-band frequency response. The SINAD figure circulated in the thread is 116 dB, at a 2.0 Vrms output. SMSL's published specs are THD+N 0.00013% (−117 dB) and 121 dB dynamic range and SNR.
⚠ vs. listeners — Two small tensions, neither of which moved the consensus. Amir calls the frequency response essentially flat in the audible band, but several ASR members flagged a gentle high-frequency slope in the same graph and argued the priority is backwards — that this kind of linear distortion should outrank a few more dB of SINAD. The counter-argument in the thread is that the deviation sits at frequencies where audibility is marginal and is dwarfed by any loudspeaker. Separately, Head-Fi's reviewer describes an AKM character; nothing in the measurements distinguishes this converter from any other transparent one.
Sources split, and the split tracks how you power the thing. On the bench the SU-1 is silent — ASR's dynamic-range measurement shows transparency achieved for noise as well as distortion, and Amazon's sound-quality tally runs 180 positive to 37 negative across 217 mentions. But three independent sources report the same specific artefact: audible clicks or digital noise between tracks, or when the sample rate changes, with the DAC drawing its power from a computer's USB port. A video reviewer lists it as the unit's only con. A dealer who ran it two ways found the pops on his mini-PC and no pops once he moved to a separate supply with the signal over coax or optical. An owner running Windows 10 relayed the complaints and had none himself over several hours. That is the practical shape of it: not hiss, not hum, not a design fault you can see on a graph — an artefact of hanging an $80 USB-powered DAC off a noisy port, with a known workaround.
Measured
ASR measured dynamic range, IMD and jitter with no audible concern: distortion and noise both reach full transparency, and the jitter spikes present are described as negligible. No bench test of the reported USB-power artefact exists — it is a system-level effect, not something the analyser sees at the RCA jacks.
⚠ vs. listeners — The bench and the complaint are not actually in conflict; they are measuring different things. Amir's figures describe the converter fed a clean signal, while the pops appear at the boundary between the host computer's USB port and a device that takes both data and power from it. Amir noted in the thread that USB-only power is a deliberate cost saving and that either approach is fine "as long as it doesn't compromise fidelity" — which is precisely the line the affected owners say gets crossed on their machines.
Where it splits
dead quiet in normal use — the measured noise floor is the whole story71%
“Performance is superb for the cost as it provides full transparency to the source.”
amirm, Audio Science Review
clicks and digital noise between tracks when USB-powered from a computer29%
“When plugging the SU-1 into my desktop system directly via USB-C I could hear pops and other noise when switching between higher/ lower bandwidth (bit rate) recordings”
vAudio Architect
The most decision-relevant disagreement here, and unusually for a budget product it has a named cause. Everyone who handled one calls the case good: CNC aluminium, anodised, chamfered edges, no gaps or burrs, rubber feet that keep it planted under stiff RCA cables. Against that, Amazon's per-topic tally on the same listing that produces a 4.2 average runs 25 negative to 5 positive on durability across 30 mentions — the only topic on the page that inverts — with owners describing units dying at two, three and six months, sometimes replacements dying too, and typically past the return window. A 2026 ASR thread walks one such failure through a full elimination test and lands on a specific part: the 5 V to ±12 V DC/DC converter module, which members there describe as the unit's common point of failure and a €3–7 replacement for anyone able to solder. The same member is careful to add that the rest of the device is robust. Both things are true, which is why they are camps and not a verdict.
Measured
No reliability testing exists for this class of product, so the closest thing to a rate is Amazon's own topic breakdown on the listing: 30 customers mention durability, 5 positive and 25 negative — against 180/37 on sound quality, 141/29 on performance and 136/13 on value for money on the same page. The failure signature owners describe (volume collapses, heavy distortion, the unit still powers on) matches the DC/DC-converter diagnosis offered on ASR.
Where it splits
the case and connectors punch well above $8065%
“The housing also has an anodized finish with nicely chamfered edges, giving it a premium stealthy aesthetic.”
Meldrick, Headfonics
a meaningful share die within months, at one identified component35%
“That specific converter is indeed the common point of failure in the SU-1.”
Roland68, Audio Science Review
Features
Strong consensus · 7 srcBroad agreement on a mixed picture, which is why it reads as consensus rather than argument. The generous half: three digital inputs — USB-C, TOSLINK and coaxial — is more than most rivals give you at this price, and it makes the SU-1 a hub for a PC, a TV or console and a CD transport at once. USB carries 32-bit/768 kHz PCM and DSD512; optical and coax cap at 24/192. MQA and MQA-CD decoding is included, which several ASR members would happily trade back for a lower price. The bare half, which nobody disputes: no volume control, no remote, no balanced output, no filters, no display, no sample-rate indication, and no 5 V power adapter in the box. Amir had to correct the record on the remote in his own thread, because retail listings and SMSL's own marketing have said otherwise. The one real gotcha is power: the USB port is the unit's only source of it, so running optical or coax still means finding a spare charger, and you cannot separate data and power without a splitter. Amazon's compatibility tally is the closest thing to a red flag — 20 positive to 16 negative, mostly people who could not get USB working with a particular device and fell back to optical.
“This is an impressive suite of inputs especially at a sub-100 USD price point”
Meldrick, Headfonics
“There is no remote here folks. Don't know why the description says otherwise.”
amirm, Audio Science Review
“Note that you need to have a USB power supply even if you use non-USB input (it is the only source of power).”
amirm, Audio Science Review
“Most people would probably want a remote & volume control included, but beyond that I can't fault it!”
Robbo99999, Audio Science Review
Measured
Manufacturer specification, consistent across Headfonics, MOONSTAR and the Head-Fi listing: AKM AK4493S converter, XMOS XU-316 USB interface, 2.0 Vrms single-ended output, USB 32-bit/768 kHz PCM and DSD512, optical and coaxial 24-bit/192 kHz, MQA to 16×, <5 W consumption, 96 × 27 × 78 mm, 195 g.
Ergonomics
Moderate · 7 srcMostly praised, with the reservations you would expect of a box with one button. The single front control powers the unit when held and cycles the three inputs when tapped, with LEDs for each source plus an MQA indicator — Headfonics found it usable in a dim room, and Amazon's ease-of-use tally is 29 positive to 1 negative. It is small enough that one owner measured it against a deck of cards, and it needs no drivers on macOS, Linux, Android or iOS. The complaints are consistent rather than contradictory: there is no indication of what sample rate is arriving, so you cannot tell whether something upstream is resampling you; the right-channel RCA is not colour-coded red; the unit is light enough that only the rubber feet keep it from being dragged around by heavy cables; and the plain black slab is not going to earn a spot on the front of a rack. Owners who could not get USB to enumerate on a given machine generally found optical worked immediately.
“The SU-1 has a simple and intuitive control system, with only one button on the front panel: the power switch.”
Meldrick, Headfonics
“The SU-1 has a pretty robust appearance for its price, which doesn’t show any imperfections such as gaps and burrs.”
Gökhan Aydın, MOONSTAR Reviews
The closest thing to a settled question in budget desktop audio, with one dissent worth hearing. Nine of the ten sources treat $80 as the floor below which a competent standalone DAC stops existing: ASR closes with a recommendation and the line that there is no more excuse for bad DAC performance, one member argues anything costing more with worse numbers should go back to engineering, Headfonics calls it hard to beat under $100, and Amazon's value tally is 136 positive to 13 negative. The owner who compared it to a $2,500 CD player concluded the only reason left to spend more is I/O he does not need. The dissent comes from the reliability side: the owner whose unit failed at four months, out of an AliExpress warranty window he could not reopen, ended his thread with the observation that buying cheap can cost you twice — and ASR's regulars broadly agreed that an $80 box that dies is landfill, because returning it costs more than replacing it. Both readings survive: it is an extraordinary amount of measured performance per dollar, bought in a class where a failure is usually not worth fixing.
“As a sub-$100 dedicated DAC, the SMSL SU-1 is hard to beat.”
Meldrick, Headfonics
“Any DAC that costs +US$80, that has performance less than this, should be sent back to engineering.”
sweetchaos, Audio Science Review
“For me, the only reason to spend more on a DAC would be to get functions and I/O that the SU-1 doesn't have.”
Mark Rehorst
“I think we all have to accept that bargains like this are landfill if they fail, as they usually have to go back to China and from 'the west,' it's extremely expensive to return.”
DSJR, Audio Science Review
