Short answer: the SMSL SU-2. It ranks #18 of 30 DACs by measured performance, rated 4.7/5, at $99.99; the SMSL SU-6 ranks #20, rated 4.6/5, and costs $169.99, which makes this an easy call rather than a real tradeoff.
Why pick the SMSL SU-2: Audio Science Review measured 123 dB SINAD, so its noise and distortion are transparent. The tradeoff: There is no USB input listed, so a computer needs a separate USB to digital converter.
The case for the SMSL SU-6: Audio Science Review measured a SINAD of 118 dB, so its noise and distortion are inaudible. Watch for: It has only RCA outputs, with no balanced XLR.
Buy the SMSL SU-2. It is rated higher than the SMSL SU-6 and costs less, so it is the default pick unless a specific strength of the other one matters more to you.
Looking for alternatives? See the complete Headphone Amps and DACs rankings.
Specifications Side By Side
| SMSL SU-2 | SMSL SU-6 | |
|---|---|---|
| Price | $99.99 | $169.99 |
| Ranked | #18 of 30 in DACs | #20 of 30 in DACs |
| Device Type | DAC | DAC |
| SINAD | 123 dB (measured by Audio Science Review) | 118 dB (measured by Audio Science Review) |
| Balanced Output | Yes (XLR line out) | No |
| Inputs | AES/EBU, optical, coaxial | USB, optical, coaxial, Bluetooth |
| Outputs | RCA, XLR | RCA |
| DAC Chip | ES9039Q2M | ES9038Q2M |
| Dimensions | 5.9” x 1.7” x 5.2” (150 x 42.5 x 133.1 mm) | 5.5” x 1.1” x 4.1” (140 x 28 x 105 mm) |
| Weight | 1.2 lbs (533 g) | 0.8 lbs (350 g) |
| Bluetooth Codecs | - | SBC, AAC, aptX, aptX HD, LDAC |
Related Amp and DAC Comparisons
How SMSL SU-2 compares with other leading options:
- Fosi Audio ZD3 vs SMSL SU-2
- SMSL SU-2 vs SMSL PS200 PRO
- SMSL SU-2 vs SMSL SU-1
- SMSL SU-2 vs Topping E30 II Lite
- SMSL SU-2 vs Fosi Audio Q6
Prices on this page were last checked October 11, 2026 at 4:59 PM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.
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The Two Amps and DACs In Full
SMSL SU-2: $99.99 Amazon eBay
Pros: Audio Science Review measured 123 dB SINAD, so its noise and distortion are transparent. It sends RCA and XLR outputs to an amp or powered speakers, and accepts AES/EBU, optical and coaxial digital sources. It matches the rating of the Topping Centaurus and measures cleaner for a small fraction of the price.
Cons: There is no USB input listed, so a computer needs a separate USB to digital converter. It has no Bluetooth or volume control, and the SMSL D-6S rates higher with USB and LDAC Bluetooth for more money.
Full SMSL SU-2 review and specifications →
| Released | Jan 2026 (9 months ago) |
|---|---|
| Balanced Output | Yes (XLR line out) |
| DAC Chip | ES9039Q2M |
| Device Type | DAC |
| Dimensions | 5.9” x 1.7” x 5.2” (150 x 42.5 x 133.1 mm) |
| Inputs | AES/EBU, optical, coaxial |
| Outputs | RCA, XLR |
| SINAD | 123 dB (measured by Audio Science Review) |
| Weight | 1.2 lbs (533 g) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
SMSL SU-6: $169.99 Amazon eBay
Pros: Audio Science Review measured a SINAD of 118 dB, so its noise and distortion are inaudible. It accepts USB, optical, coaxial and Bluetooth with LDAC, aptX HD and AAC, which makes it a flexible source for powered speakers or a separate amp. It is compact at 140 x 105 mm and 350 g.
Cons: It has only RCA outputs, with no balanced XLR. The SMSL SU-2 rates higher and measures cleaner at 123 dB for less. No volume control is listed, so it relies on the connected amp or speakers.
Full SMSL SU-6 review and specifications →
| Released | Nov 2021 (4 years ago) |
|---|---|
| Balanced Output | No |
| Bluetooth Codecs | SBC, AAC, aptX, aptX HD, LDAC |
| DAC Chip | ES9038Q2M |
| Device Type | DAC |
| Dimensions | 5.5” x 1.1” x 4.1” (140 x 28 x 105 mm) |
| Inputs | USB, optical, coaxial, Bluetooth |
| Outputs | RCA |
| SINAD | 118 dB (measured by Audio Science Review) |
| Weight | 0.8 lbs (350 g) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons