Short answer: the SMSL SU-2. It ranks #18 of 30 DACs by measured performance, rated 4.7/5, at $99.99. The Fosi Audio Q6 ranks #25, rated 4.5/5, at $84.99, $15 cheaper, a saving that is not big enough to make up the sound-quality gap.
What the SMSL SU-2 does well: Audio Science Review measured 123 dB SINAD, so its noise and distortion are transparent. Watch for: There is no USB input listed, so a computer needs a separate USB to digital converter.
What the Fosi Audio Q6 does well: Audio Science Review measured 115 dB SINAD, so its noise and distortion are transparent. Watch for: There are no balanced outputs and no volume control, so it needs an amp or speakers with their own volume.
Buy the SMSL SU-2. It is rated higher, and the $15 you would save on the Fosi Audio Q6 does not close the gap.
Still deciding? The full Headphone Amps and DACs rankings cover every ranked option.
Specifications Side By Side
| SMSL SU-2 | Fosi Audio Q6 | |
|---|---|---|
| Price | $99.99 | $84.99 |
| Ranked | #18 of 30 in DACs | #25 of 30 in DACs |
| Device Type | DAC | DAC |
| SINAD | 123 dB (measured by Audio Science Review) | 115 dB (measured by Audio Science Review) |
| Balanced Output | Yes (XLR line out) | No |
| Inputs | AES/EBU, optical, coaxial | USB-C, optical, coaxial |
| Outputs | RCA, XLR | RCA, sub out |
| DAC Chip | ES9039Q2M | AK4493S |
| Dimensions | 5.9” x 1.7” x 5.2” (150 x 42.5 x 133.1 mm) | - |
| Weight | 1.2 lbs (533 g) | - |
| Volume Control | - | None (fixed-level DAC) |
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 SU-6
- SMSL SU-2 vs SMSL PS200 PRO
- SMSL SU-2 vs SMSL SU-1
- SMSL SU-2 vs Topping E30 II Lite
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
Fosi Audio Q6: $84.99 Amazon eBay
Pros: Audio Science Review measured 115 dB SINAD, so its noise and distortion are transparent. It takes USB-C, optical and coaxial inputs and feeds an amp or powered speakers over RCA, with a separate sub out for adding a subwoofer. It matches the rating of the SMSL PS200 PRO for slightly less.
Cons: There are no balanced outputs and no volume control, so it needs an amp or speakers with their own volume. The SMSL SU-2 rates higher with lower measured distortion and XLR outputs for a little more.
Full Fosi Audio Q6 review and specifications →
| Released | Apr 2025 (1 year ago) |
|---|---|
| Balanced Output | No |
| DAC Chip | AK4493S |
| Device Type | DAC |
| Inputs | USB-C, optical, coaxial |
| Outputs | RCA, sub out |
| SINAD | 115 dB (measured by Audio Science Review) |
| Volume Control | None (fixed-level DAC) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons