Short answer: the SMSL M10. It ranks #36 of 43 DAC and headphone amp combos by measured performance, rated 3.3/5, at $455. The Pro-Ject Pre Box S2 Digital ranks #38, rated 2.9/5, at $399, $56 cheaper, not enough of a saving to outweigh the sound-quality gap.
The SMSL M10 is the better-sounding option. It has balanced 4-pin XLR headphone and XLR line outputs alongside a 6.35 mm jack, plus USB, optical and coaxial inputs. The tradeoff: Audio Science Review measured 95 dB SINAD, fine for most headphones but sensitive in-ear monitors may reveal hiss or noise.
What the Pro-Ject Pre Box S2 Digital does well: It accepts USB, optical and coaxial inputs and also works as a preamp with a variable RCA output, all in a compact box about the size of a paperback. Watch for: Pro-Ject rates it at only 68 mW into 32 ohms, which suits in-ear monitors and easy headphones but not demanding full-size models.
Buy the SMSL M10. It is rated higher, and the $56 saving on the Pro-Ject Pre Box S2 Digital is not enough to make up the difference.
Still deciding? The full Headphone Amps and DACs rankings cover every ranked option.
Specifications Side By Side
| SMSL M10 | Pro-Ject Pre Box S2 Digital | |
|---|---|---|
| Price | $455.00 | $399.00 |
| Ranked | #36 of 43 in DAC and Headphone Amp Combos | #38 of 43 in DAC and Headphone Amp Combos |
| Device Type | DAC and headphone amp | DAC and headphone amp |
| SINAD | 95 dB (measured by Audio Science Review) | 100 dB (measured by Audio Science Review) |
| Output Power (32 ohms) | 340 mW (manufacturer rated, balanced) | 68 mW (manufacturer rated) |
| Output Power (300 ohms) | 87 mW (manufacturer rated, balanced) | - |
| Headphone Outputs | 6.35 mm, 4-pin XLR balanced | 6.35 mm |
| Balanced Output | Yes (4-pin XLR, XLR line out) | No |
| Inputs | USB-B, optical, coaxial | USB-B, optical, coaxial |
| Outputs | RCA, XLR | RCA (variable) |
| DAC Chip | AK4497 | 2 x ES9038Q2M |
| Dimensions | 9.8” x 2” x 8.1” (250 x 50 x 205 mm) | 4.1” x 1.5” x 4.8” (103 x 37 x 122 mm) |
| Volume Control | - | Hardware knob |
| Weight | - | 0.8 lbs (366 g) |
Related Amp and DAC Comparisons
More worthwhile head-to-heads for SMSL M10:
- Chord Mojo 2 vs SMSL M10
- Qudelix T71 vs SMSL M10
- Neutron HiFi DAC V1 vs SMSL M10
- xDuoo XA-10 vs SMSL M10
- SMSL M10 vs Essence HDACC II-4K
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.
As an eBay Partner, we may be compensated if you make a purchase.
The Two Amps and DACs In Full
SMSL M10: $455.00 Amazon eBay
Pros: It has balanced 4-pin XLR headphone and XLR line outputs alongside a 6.35 mm jack, plus USB, optical and coaxial inputs. SMSL rates it at 340 mW balanced into 32 ohms, enough for most headphones.
Cons: Audio Science Review measured 95 dB SINAD, fine for most headphones but sensitive in-ear monitors may reveal hiss or noise. The Qudelix T71 rates higher with better measured SINAD for less, and there is no Bluetooth input.
Full SMSL M10 review and specifications →
| Balanced Output | Yes (4-pin XLR, XLR line out) |
|---|---|
| DAC Chip | AK4497 |
| Device Type | DAC and headphone amp |
| Dimensions | 9.8” x 2” x 8.1” (250 x 50 x 205 mm) |
| Headphone Outputs | 6.35 mm, 4-pin XLR balanced |
| Inputs | USB-B, optical, coaxial |
| Output Power (300 ohms) | 87 mW (manufacturer rated, balanced) |
| Output Power (32 ohms) | 340 mW (manufacturer rated, balanced) |
| Outputs | RCA, XLR |
| SINAD | 95 dB (measured by Audio Science Review) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
Pro-Ject Pre Box S2 Digital: $399.00 Amazon eBay
Pros: It accepts USB, optical and coaxial inputs and also works as a preamp with a variable RCA output, all in a compact box about the size of a paperback. Audio Science Review measured a SINAD of 100 dB, which is fine for most headphones.
Cons: Pro-Ject rates it at only 68 mW into 32 ohms, which suits in-ear monitors and easy headphones but not demanding full-size models. At 100 dB SINAD, sensitive in-ears may reveal some hiss, it has no balanced outputs, and the Neutron HiFi DAC V1 rates higher and measured cleaner for less.
Full Pro-Ject Pre Box S2 Digital review and specifications →
| Released | 2017 (9 years ago) |
|---|---|
| Balanced Output | No |
| DAC Chip | 2 x ES9038Q2M |
| Device Type | DAC and headphone amp |
| Dimensions | 4.1” x 1.5” x 4.8” (103 x 37 x 122 mm) |
| Headphone Outputs | 6.35 mm |
| Inputs | USB-B, optical, coaxial |
| Output Power (32 ohms) | 68 mW (manufacturer rated) |
| Outputs | RCA (variable) |
| SINAD | 100 dB (measured by Audio Science Review) |
| Volume Control | Hardware knob |
| Weight | 0.8 lbs (366 g) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons