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Pro-Ject Head Box S2 Digital

DAC/headphone amp

Item # 252HBXS2DS

The versatile Head Box S2 Digital uses an audiophile-grade DAC chip to give richness and detail to your favorite tunes.

The versatile Head Box S2 Digital uses an audiophile-grade DAC chip to give richness and detail to your favorite tunes.

Item # 252HBXS2DS

In stock

$299.00 -$50.00 Special purchase


Other options

60-day returns

If you don't love it, send it back.

Since 1974

Years of experience making people happy.

60-day price protection

We’ll reimburse you if the price drops.

About the Pro-Ject Head Box S2 Digital

Get the most from your digital tunes

This ultra-compact component can give your headphone setup a nice boost, and it won't take up much room on your desktop. Pro-Ject's Head Box S2 Digital was built to deliver top-notch sound quality from digital sources, and it has ample power for most cans. Its sleek aluminum chassis houses audiophile-grade components and offers versatile input and output connections. It even has five built-in digital filters to help you tailor its sound to your liking. 

Get the most from your digital tunes

This ultra-compact component can give your headphone setup a nice boost, and it won't take up much room on your desktop. Pro-Ject's Head Box S2 Digital was built to deliver top-notch sound quality from digital sources, and it has ample power for most cans. Its sleek aluminum chassis houses audiophile-grade components and offers versatile input and output connections. It even has five built-in digital filters to help you tailor its sound to your liking. 

Simple, effective front-panel layout

The front panel has a tactile knob for making precise volume adjustments. It also has buttons for selecting which digital input and filter setting you'd like to use, along with corresponding LED indicators. There's also an LED indicator that lights up if you're streaming DSD files. You'll find a full-sized 1/4" headphone jack on the left side for connecting a pair of headphones.

Connection versatility

There are three digital inputs on the back: optical digital, coaxial digital, and USB Type-B. This last input is the one you'll use if you have some serious high-res files — it supports PCM-based files up to 32-bit/768kHz and DSD up to 11.2MHz (DSD256).The Head Box S2 Digital also double-filters USB power noise to prevent the signal from being muddied.

Don't plan on using headphones but still want the sonic benefits of the internal DAC? No worries — the Head Box is a versatile machine. You'll find a pair of stereo RCA outputs you can use to tie it into your stereo receiver, integrated amp, or home theater receiver. 

The Head Box S2 Digital can be powered directly off the rear USB Type-B input. If you'd rather power it from a wall outlet, a power supply is included.

Inside the chassis

Pro-Ject went all out on the Head Box S2 Digital's internal components. On its gold-plated four-layer printed circuit board, you'll find an ESS Sabre ES9038Q2M premium digital-to-analog converter chip, as well as an ESS9063 headphone amplifier/output buffer chip. The 9038Q2M is one of the most impressive digital-to-analog converters out there, boasting a super-low noise floor, fast processing, and jitter (digital timing distortion) that's practically negligible. The ESS9063 takes on the duty of powering your headphones and does a fantastic job. It can handle higher impedance headphones without breaking a sweat, all while maintaining low distortion. 

Hands-on with the Head Box S2 Digital

The original Head Box was a neat DAC. Its deceptively simple appearance hid the excellent sound quality contained inside. When I saw that Pro-Ject was releasing a second-generation Head Box (and found out I'd get a chance to play with it), I was excited to put it through its paces and see how it performed.

Sleek, space-saving design

It had been a while since I played with a Head Box DAC. When I unboxed this new version, I realize I had forgotten just how small they are. The S2 Digital was lightweight and just big enough to fit in the palm of my hand, sporting an eye-catching silver finish.

After scrambling to find a USB Type B cable, I hooked up my Focal Elegia over-ear headphones, fired up TIDAL on my desktop, and got to work. I wanted to try out a live track first to see how revealing the DAC was, so I started things off with “Life During Wartime” off Talking Head's Stop Making Sense.

Using the selectable filters

One of the neat things about the Head Box S2 Digital is that it comes equipped with five different digital filters. I like it when my gear gives me options, and I found choosing the best digital filter for my ears to be fun. Going back and forth between them on the track, some filters sounded fuller than others. Some had more bass, others had more of a midrange/treble emphasis. I found that option 4 ("Minimum Phase Slow Roll Off")had the best sound for my tastes.

After setting the filter, I restarted the song to get a feel for the DAC's performance. Notably, the track had some real groove to it that other DACs can have some difficulty resolving. David Byrne's quirky-but-loveable singing felt realistic, heard cleanly over the cheers of the crowd and the band. I could tell the guitar was on the right side of the stage and the drums were neatly placed center stage, behind David. The imaging and stereo separation left a positive impression and added a lot of life to an already great live performance.

Testing dynamic extremes

Spiritbox's “Sunkiller” is a haunting metal track that lulls you in with its calm, airy melody before doing a 180 and getting super-heavy in the last minute and a half of the song. Naturally, I wanted to see how well the DAC would handle a track like that since the sudden switch can muddy things. Courtney LaPlante's chilling performance was accentuated nicely by the Pro-Ject. There was an almost silky smoothness to her voice that elevated the experience. The crescendo at the end was spectacular. I was impressed by how well the S2 was able to switch from calm to frenetic without losing detail or quality.

Smooth highs

I wrapped things up with “Dance Monkey” by Tones and I — a pop track that juxtaposes deceptively playful music with somber lyrics. I'm pleased to report that the Head Box S2 made the track a lot of fun to listen to. The brightness in Toni Watson's unique performance came through with no noticeable ear fatigue. With some other DACs, her higher-pitched voice can sound grating. The bass was punchy and articulate, and I found myself bobbing my head to it as the song went on.


Product highlights:

  • Featured in our article: Best DACs for 2023
  • premium ESS Sabre ESS9038Q2M digital-to-analog converter chip
  • front-panel source button to change between inputs
  • five selectable digital filter options for fine-tuning your sound
    • selected filters and inputs are stored after the unit is turned off
  • aluminum/metal chassis
  • front-panel volume knob allows for minute volume adjustments
  • supported sample rates:
    • optical digital: up to 24-bit/96kHz
    • USB: up to 32-bit/768kHz; DSD up to DSD 256 (11.2 MHz)
    • coaxial digital: up to 24-bit/96kHz
  • minimum recommended headphone impedance: 8 ohms
  • headphone output power: 68mW at 32 ohms; 6.6mW at 600 ohms
  • output voltage: 2V
  • frequency response: 20-20,000Hz
  • THD: 0.0007%
  • 1 coaxial digital input
  • 1 optical digital input
  • 1 USB Type-B input (cable sold separately )
  • unbalanced stereo RCA output
  • unbalanced 1/4" front-panel headphone output
Additional information:
  • external power supply included
  • drivers may be required for some versions of Windows® 10
  • dimensions (measured by Crutchfield): 4-1/16"W x 1-7/16"H x 5-3/4"D (including volume knob and rear connections)
  • weight: 0.81 lbs. (without power supply)
  • warranty: 2 years
  • Our 60-day money-back guarantee
  • MFR # PRO2040013

What's in the box:

  • Headphone amplifier (silver)
  • AC adapter with attached 45" DC output cord and Micro USB plug (DC output: 5.0V 1.0A)
  • 3 AC plug adapters (US/Euro/UK)
  • Instructions for Use (English)
  • Instructions (German)
  • CD with USB driver for Windows

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Pro-Ject Head Box S2 Digital reviews

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More details on the Pro-Ject Head Box S2 Digital

Research Team

Features & specs

Type Desktop/Component
Built-in Rechargable Battery No
Built-in DAC Yes
Amplifier Output Specs
Output Power 6.6mW, 68mW
Output Impedance (Unbalanced) 600 ohm, 32 ohm
Output Impedance (Balanced) N/A
Audio Specs
Bit Depth (USB) 32
Max Sampling Rate (USB) 768 kHz
Bit Depth (S/PDIF) 24
Max Sampling Rate S/PDIF 192 kHz
S/N Ratio (Unbalanced, in dB) 0
S/N Ratio (Balanced, in dB) 0
THD (Unbalanced) 0.0007%
THD (Balanced) N/A
Supported File Types
PCM Up to 768kHz
Total Inputs 3
USB Type B
Optical Digital 1
Coaxial Digital 1
3.5mm Digital None
Stereo RCA Analog None
Stereo 3.5mm Analog None
Stereo XLR Analog None
Headphone Outputs
3.5mm Unbalanced None
1/4-inch Unbalanced 1
4.4mm Balanced None
XLR4 Balanced None
Other Headphone Outs None
Line Level & Digital Outs
RCA Line Out 1
3.5mm Line Out None
XLR Line Out None
Subwoofer Out None
Optical Digital Out None
Coaxial Digital Out None
Wireless Connectivity
Bluetooth No
Wi-Fi No
Apple-compatible No
Android-compatible No
General Info
Width (inches) 4-1/16
Height (inches) 1-7/16
Depth (inches) 5-13/16
Weight 0.814 lbs.
Parts Warranty 2 Years
Labor Warranty 2 Years

Product Research


Overview: The Pro-Ject Head Box S2 Digital headphone amplifier has a built-in DAC (digital-to-analog converter). The headphone amp can drive your headphones to higher volumes and better sound quality than the built-in headphone outputs on your home receiver, computer, TV, or audio player. It has three digital inputs (USB, optical, and coaxial) that support up to 32-bit/768kHz decoding and DSD256 (USB). Dimensions: Width 4.013", Height 1.405", Depth 4.778" (7.783" with plugs), Weight 13.05 ounces.

Construction: The Pro-Ject Head Box S2 Digital headphone amplifier is equipped with the high-end ESS Sabre ESS9038 32-bit DAC. It employs a silver aluminum/metal case to shields the circuitry from vibration and electromagnetic interference. It has the same form factor as other Pro-Ject electronic components, such as the Pre Box S2, Amp Box S2, and the Stereo Box S2.

Inputs: The Head Box S2 offers three digital inputs: USB (Type B), Optical (Toslink), and Coaxial (RCA). The USB input is designed for use with a computer (Windows/Mac), and can support PCM up to 32-bit/768kHz and DSD playback up to DSD256 (Quad DSD). The optical and coaxial digital inputs support PCM up to 24-bit/192kHz playback from digital sources like CD players, music streamers, or TVs. You can select the desired input by pressing the Input Selector button on the front panel until the LED indicates your selection: 1 (optical), 2 (coaxial) or 3 (USB). When streaming DSD data over the USB input, the DSD LED indicator on the front panel will glow.

USB Driver: A USB driver is required for Windows operating systems. You can easily download the driver from the Pro-Ject website or from the included CD). Mac OS operating systems do not need an additional driver.

Filters: The headphone amplifier offers five digital filters to shape the sound to your listening preference. You can choose the preferred filter by repeatedly pressing the Filter button on the front panel. When you turn off the unit, the selected filter is stored for the next use. The filters are numbered as follows:

  1. Optimal Transient
  2. Fast Roll Off (Linear Phase Fast Roll Off)
  3. Slow Roll Off (Linear Phase Slow Roll Off)
  4. Minimum Phase (Minimum Phase Slow Roll Off)
  5. Apodizing Hybrid

Headphone Output: The Pro-Ject Head Box S2 Digital headphone amplifier is equipped with a front-panel 1/4" (6.3mm) headphone jack (unbalanced) to plug in your headphones. The headphone jack accepts headphones with impedances between 8Ω and 600Ω. The headphone output is rated from 6.6mW at 600Ω and 68mW at 32Ω. A large rotary volume knob on the front panel lets you control the volume of your connected headphones.

RCA Output: The Head Box S2 features a gold-plated stereo RCA output on the rear panel, which lets you connect the unit to a power amplifier. The RCA output is muted when a pair of headphones are connected.

Volume Control: The headphone amplifier features a front-panel rotary volume knob to control the volume level of your connected headphones or power amplifier.

Power Requirements: The Pro-Ject Head Box S2 Digital headphone amplifier is powered by the supplied AC adapter (5V DC / 1A). If you are using the USB input, you should disconnect the AC adapter and power the unit directly from the connected computer via the USB input.


  • Frequency Response: 20Hz - 20kHz
  • THD: 0.0007% (at 0dB, 2V RMS, 1kHz)
  • Dynamic Range: 120 dBA
  • Headphone Jack: 1/4" (6.3mm)
  • Headphone Output: 68mW (32 ohms); 6.6mW (600 ohms)
  • Line Output: Stereo RCA
  • Line Output Voltage: 2.05 V (effective)
  • Digital Inputs:
    • USB: PCM up to 32-bit/768kHz, DSD up to DSD256
    • Coaxial: PCM up to 24-bit/192kHz
    • Optical: PCM up to 24-bit/192kHz

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Customer Q&A

2 questions already asked

Does the volume knob adjust the sound volume in windows or is it a separate volume adjustment?
[ Aaron  Nov 06, 2022 ]
1 answer
You'll need to download the Pro-Ject Windows driver to connect this fantastic Head Box S2 Digital to your PC Aaron. I can confirm that this will bypass your computer's soundcard/DAC in favor of the Head Box S2, but I cannot confirm if that volume control is linked to the Window's volume. I hope this was helpful.
[ Bo  Nov 07, 2022 ]  Staff
Does the volume control also affect the RCA line out?
[ Drew  Aug 06, 2022 ]
1 answer
The RCA line out is controlled by the volume knob.
[ Nemo  Aug 07, 2022 ]  Staff

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