Short answer: the Pro-Ject Pre Box S2 Digital, though neither ranks well in its class. It ranks #38 of 43 DAC and headphone amp combos by measured performance, rated 2.9/5, at $399. The Leckerton Audio UHA-6S.MKII ranks #40, rated 2.5/5, at $239, $160 cheaper, which does not close the gap in measured performance. Both are rated below 3.0/5 among the 43 DAC and headphone amp combos, and the D&A Alpha, ranked #2 at $399, is a better place to start if measured performance matters.
The Pro-Ject Pre Box S2 Digital is the better-sounding pick. 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. The tradeoff: 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.
Why pick the Leckerton Audio UHA-6S.MKII: It is a portable battery powered DAC and amp with micro USB, optical, coaxial and 3.5 mm analog inputs, lasting 10 hours from digital sources and 30 hours in analog mode. The catch: It is rated for only 55 mW into 32 ohms with its stock op amp, which suits in-ear monitors and easy headphones only, and sensitive in-ears may reveal hiss at 94 dB SINAD.
Buy the Pro-Ject Pre Box S2 Digital. It is rated higher, and saving $160 with the Leckerton Audio UHA-6S.MKII does not make up for the sound-quality gap.
Looking for alternatives? See the complete Headphone Amps and DACs rankings.
Specifications Side By Side
| Pro-Ject Pre Box S2 Digital | Leckerton Audio UHA-6S.MKII | |
|---|---|---|
| Price | $399.00 | $239 |
| Ranked | #38 of 43 in DAC and Headphone Amp Combos | #40 of 43 in DAC and Headphone Amp Combos |
| Device Type | DAC and headphone amp | DAC and headphone amp |
| SINAD | 100 dB (measured by Audio Science Review) | 94 dB (measured by Audio Science Review) |
| Output Power (32 ohms) | 68 mW (manufacturer rated) | 55 mW (manufacturer rated, stock AD8610 op-amp; 140 mW with AD8620) |
| Headphone Outputs | 6.35 mm | - |
| Balanced Output | No | No |
| Inputs | USB-B, optical, coaxial | Micro USB, optical, coaxial, 3.5 mm analog |
| Outputs | RCA (variable) | - |
| DAC Chip | 2 x ES9038Q2M | Cirrus Logic CS4398 |
| Volume Control | Hardware knob | Analog |
| Dimensions | 4.1” x 1.5” x 4.8” (103 x 37 x 122 mm) | 2.8” x 0.8” x 4.2” (70 x 20 x 106 mm) |
| Weight | 0.8 lbs (366 g) | 0.4 lbs (170 g) |
| Output Power (300 ohms) | - | 40 mW (manufacturer rated) |
| Battery Life | - | 10 hours (USB/digital), 30 hours (analog) |
Related Amp and DAC Comparisons
More worthwhile head-to-heads for Pro-Ject Pre Box S2 Digital:
- Chord Mojo 2 vs Pro-Ject Pre Box S2 Digital
- xDuoo XA-10 vs Pro-Ject Pre Box S2 Digital
- SMSL M10 vs Pro-Ject Pre Box S2 Digital
- Essence HDACC II-4K vs Pro-Ject Pre Box S2 Digital
- Pro-Ject Pre Box S2 Digital vs xDuoo DM-01
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
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
Leckerton Audio UHA-6S.MKII: $239 Leckerton Audio eBay
Pros: It is a portable battery powered DAC and amp with micro USB, optical, coaxial and 3.5 mm analog inputs, lasting 10 hours from digital sources and 30 hours in analog mode. Audio Science Review measured a SINAD of 94 dB, fine for most headphones.
Cons: It is rated for only 55 mW into 32 ohms with its stock op amp, which suits in-ear monitors and easy headphones only, and sensitive in-ears may reveal hiss at 94 dB SINAD. It has no balanced output and still uses micro USB. The Pro-Ject Pre Box S2 Digital rates higher and measures cleaner, though it costs more.
Full Leckerton Audio UHA-6S.MKII review and specifications →
| Balanced Output | No |
|---|---|
| Battery Life | 10 hours (USB/digital), 30 hours (analog) |
| DAC Chip | Cirrus Logic CS4398 |
| Device Type | DAC and headphone amp |
| Dimensions | 2.8” x 0.8” x 4.2” (70 x 20 x 106 mm) |
| Inputs | Micro USB, optical, coaxial, 3.5 mm analog |
| Output Power (300 ohms) | 40 mW (manufacturer rated) |
| Output Power (32 ohms) | 55 mW (manufacturer rated, stock AD8610 op-amp; 140 mW with AD8620) |
| SINAD | 94 dB (measured by Audio Science Review) |
| Volume Control | Analog |
| Weight | 0.4 lbs (170 g) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons