Short answer: the Fosi Audio ZD3. It ranks #15 of 30 DACs by measured performance, rated 4.8/5, at $179.99. The SMSL SU-6 ranks #20, rated 4.6/5, at $169.99, $10 cheaper, which does not close the gap in measured performance.
What the Fosi Audio ZD3 does well: Audio Science Review measured 117 dB SINAD, so its noise and distortion are transparent. The catch: Its SINAD is a few dB behind similarly rated DACs like the SMSL D-6S, though both are transparent.
The case for the SMSL SU-6: Audio Science Review measured a SINAD of 118 dB, so its noise and distortion are inaudible. It supports LDAC Bluetooth, which the Fosi Audio ZD3 lacks. The tradeoff: It has only RCA outputs, with no balanced XLR.
Buy the Fosi Audio ZD3. It is rated higher, and saving $10 with the SMSL SU-6 does not make up for the sound-quality gap.
Still deciding? The full Headphone Amps and DACs rankings cover every ranked option.
Specifications Side By Side
| Fosi Audio ZD3 | SMSL SU-6 | |
|---|---|---|
| Price | $179.99 | $169.99 |
| Ranked | #15 of 30 in DACs | #20 of 30 in DACs |
| Device Type | DAC | DAC |
| SINAD | 117 dB (measured by Audio Science Review) | 118 dB (measured by Audio Science Review) |
| Balanced Output | Yes (XLR line out) | No |
| Inputs | USB, HDMI ARC, optical, coaxial, Bluetooth | USB, optical, coaxial, Bluetooth |
| Outputs | RCA, XLR | RCA |
| Bluetooth Codecs | SBC, AAC, aptX, aptX HD | SBC, AAC, aptX, aptX HD, LDAC |
| DAC Chip | ES9039Q2M | ES9038Q2M |
| Volume Control | Digital preamp (remote) | - |
| Dimensions | - | 5.5” x 1.1” x 4.1” (140 x 28 x 105 mm) |
| Weight | - | 0.8 lbs (350 g) |
Related Amp and DAC Comparisons
How Fosi Audio ZD3 compares with other leading options:
- Topping D50 III vs Fosi Audio ZD3
- Fosi Audio ZD3 vs SMSL D-6S
- Fosi Audio ZD3 vs SMSL D200
- Fosi Audio ZD3 vs SMSL SU-2
- Fosi Audio ZD3 vs Soncoz LA-QXD1
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
Fosi Audio ZD3: $179.99 Amazon eBay
Pros: Audio Science Review measured 117 dB SINAD, so its noise and distortion are transparent. It has unusually broad connectivity, with USB, HDMI ARC from a TV, optical, coaxial and aptX HD Bluetooth inputs, plus RCA and XLR outputs and a remote controlled digital preamp for driving powered speakers directly. It matches the rating of the SMSL D-6S for a bit less.
Cons: Its SINAD is a few dB behind similarly rated DACs like the SMSL D-6S, though both are transparent. Bluetooth lacks LDAC, which the SMSL D-6S includes.
Full Fosi Audio ZD3 review and specifications →
| Released | Sep 2024 (2 years ago) |
|---|---|
| Balanced Output | Yes (XLR line out) |
| Bluetooth Codecs | SBC, AAC, aptX, aptX HD |
| DAC Chip | ES9039Q2M |
| Device Type | DAC |
| Inputs | USB, HDMI ARC, optical, coaxial, Bluetooth |
| Outputs | RCA, XLR |
| SINAD | 117 dB (measured by Audio Science Review) |
| Volume Control | Digital preamp (remote) |
- 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