USB Network bridge/Reclocker 

The LINK II is a digital audio bridge that accepts music files “streamed” from internet subscription services (like Spotify, Tidal, Qobuz etc.) or music files that you might already own and links them to your HiFi system.

Stack Audio has always been focused on source devices, after all, it’s where everything starts. Introduce noise and distortion at the start of the playback process, it damages and disrupts our enjoyment of the music, as a result, the LINK II has been built from the ground up to remove unwanted noise. Your favourite music sounds more realistic and immersive. The LINK II’s new clock has 50% lower phase noise in contrast with its predecessor, Stack Audio’s LINK.

Computers are plagued with noise

It is possible to take a digital signal straight from a PC or laptop and connect it to a DAC. However, as with analogue systems, digital systems can be plagued with noise.

Computers have many integrated circuits and power supplies tightly packed together with software processes running that generate noise.

This noise easily jumps onto the data bus that is used for moving files through the computer; this is often described as ‘parasitic’ noise which can effectively mask and blur the file being played back. The result of damaging the critical phase and timing information is a perceived reduction in dynamic contrast and a loss of musical nuance. This digital timing error is known as ‘jitter’ and if left untreated tends to give harshness to the sound we hear.

When it comes to hearing we, as humans, are very perceptive to phase/timing accuracy. Phase accuracy is vital to a true analogue representation of your music. Achieving true phase accuracy was John Westlake’s main focus, when designing the LINK II.

S Power

Power supplies are essential to energise circuits and make electronics work. Everything starts with power. However, if they are not implemented well, they can add noise and distortion. The LINK II’s advanced digital processors are powered by uniquely designed, exceedingly low noise, multi-stage power circuitry.

  • Three independent switching regulators are synchronized to the audio clock. This ensures that the fluctuations of the switching circuit are in time with that of the audio clock reducing fluctuations and noise interference.
  • Nine organic low resistance capacitors help filter and purify the power.
  • A triple linear regulated circuit purifies remaining noise.
  • The USB audio output and clock circuit has its own independent power rail.

S Clock

What is a clock circuit and why is a good clock circuit important?

The clock system is the heartbeat of any digital system, it manages and creates a mathematical reference for the various protocols to work from, be that Ethernet or USB.

In our world, that of digital audio file playback, multiple clocks, all running at different speeds tend to cause noise and jitter problems. We typically hear this as it gives an edgy or brittle quality to the sound.

The accuracy and reliability of the clock system, therefore, has a direct influence on the performance of the product.

The LINK II uses an ultra-low phase noise oscillator. Here at Stack Audio we went to great lengths to extract the absolute performance from this clock. It starts by powering it with an exceptionally clean supply. In addition to this, we synchronised the ethernet, USB and the PSU to the audio master clock resulting in one coherent and extremely accurate device.

This ensures that the fluctuations of the switching circuit are in time with that of the audio clock reducing fluctuations and noise. The three independent switching regulators are synchronized to the audio clock, thus when the PSU switches frequencies it is in time with the master audio clock removing clashes and interference.

Solid Aluminium Case

The LINK II is a pure digital system housed in a thick CNC machined aluminium case enclosed with EMI absorbing material. This ensures noise does not escape and enter the analogue domain nor does noise enter and affect the clock circuit.

The Software

The LINK II is designed to be as easy to use as possible. You do not need to download new software or learn a new control app to make it work, you can continue to use your favourite and familiar software to control and send music to the LINK II. Afterall companies like Roon, Audirvana, Spotify, Tidal etc. have already invested considerable resources into delivering world class software, which most of us already know how to use.

The LINK II works as an endpoint for the following protocols/programs

  • Roon
  • Audirvana
  • Squeezelite
  • Airplay® (Shairport-Sync )
  • Spotify® (Librespot)
  • HQPlayer 

The LINK II is Roon Ready certified!
60 day free Roon trial included with your LINK II

*For further information please click here 


Audio Feature Summary
  • Power circuitry is synchronized to the USB audio clock
  • Ethernet input is synchronized to the USB audio clock
  • Multi-stage ultra-low noise linear regulated power circuit
  • USB audio optimized output provides jitter free audio layback
  • The advanced clock circuitry re-clocks any USB input
Mechanical Feature Sumary
  • Machined from a solid billet of aluminum
  • Incorporates EMI absorbing material to remove internal EMI
  • The mass of the case dissipates air-borne vibration
  • Incorporates AVDC vibration trap
Communication Protocols
  • Ethernet
  • USB
  • Wi-Fi
  • Bluetooth
  • 1 x dedicated USB audio output
  • HDMI out (not i2s, or used)
Streaming Protocols
  • Roon
  • Audirvana
  • Squeezelite
  • Airplay® (Shairport-Sync)
  • Spotify® (Librespot)
  • HQPlayer (coming soon)
Supported Audio File Formats
  • Lossless: DSF (DSD), DIFF (DSD), DoP (DSD) DoP and Native DSD up to DSD 256
  • PCM Lossless: FLAC, Apple Lossless (ALAC), WAV, AIFF Compressed (lossy) Audio: MP3, AAC (in M4A container) MQA (only if DAC supports hardware unfolding) PCM up to 384 kHz /32 bits
  • Finish : Available in anodised silver or black
  • Dimensions: 174mm(W), 140mm (D), 25mm (H), 1kg (without external power supply)
  • 2 x USB inputs (Future use)
  • 1 x USB B detox input
  • Ethernet input
  • 18v 1amp- 1.5amp DC input


Made without compromise.
See what goes into making a LINK II

Press Reviews

Customer Reviews


I want to try the LINK II before I decide it’s for me?
We are really confident in the performance that we offer a 30-day money back Guarantee – see our Terms & Conditions
I do not understand what the USB power switch is for?
Not all DACs require power from the USB input, so the LINK features a USB power switch. The USB power feed is no longer active alongside the data line when this is switched off. If you’re not sure if your DAC requires power through the USB, try it switched off. If it still plays your DAC has its own power supply and the sound will benefit from having the USB power signal turned off.
Does the LINK II come with USB/Ethernet cables?
No. User requirements vary in terms of connector length and quality. We leave the choice to the user. The LINK ships with an 18V DC power supply and region appropriate plug.
I don’t use Roon. How else can I control the LINK II?
You can use the Stack Audio web interface on any device connected to your router with a web interface. You can also use third party control interfaces such as Bubble UPNP for Android and Jremote for iOS.

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