The Stack Audio LINK is a new USB music streamer. Here at Stack Audio we understand the importance of a clean audio source. Music sounds more real, enjoyable and immersive when we can remove unwanted noise, resonances and interference. These sources of extra energy are simply distortions. The LINK has been built from the ground up for noise-free playback.
The world of digital music playback can be confusing with so many different options to choose from: music files on PCs and laptops connected by USB or Wi-Fi; NAS drives on home networks with carefully archived CD libraries; internet radio and subscription services like Tidal, Qobuz, Spotify. The LINK is a universal solution that easily, simply and elegantly adds streaming capability from all these sources to existing hi-fi systems, giving you maximum flexibility.
If you are a music lover with a well-balanced system that has been refined to please your tastes, you’ll want the LINK.
NOISE IS THE ENEMY
The challenge with digital audio is avoiding noise polluting the data stream.
It is possible to take a digital signal output straight from a PC or laptop and connect it to a DAC. However, as with analogue systems, digital systems are 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 a harshness to the sound we hear.
Phase noise (blue and green areas) on an untreated PC digital output recorded on a signal integrity analyser
Humans are very perceptive when it comes to phase and timing accuracy, so it is imperative to remove unwanted elements from the incoming signal that distort or disrupt the signals phase and timing. Phase accuracy is vital to a true analogue representation of your music.
The LINK has a solution to the problem of digital noise. We worked with renowned audio electronics engineer John Westlake on the LINK streamer. With over 25 years of award-winning designs to his name in digital audio, John is the perfect partner for Stack Audio and an expert in removing noise from the signal path.
The LINK has a signal detox system that solves the problem of electromagnetic interference (EMI) and jitter damaging timing accuracy:
- Ultra-low phase noise USB audio clock
- A jitter attenuation system that synchronizes the ethernet input to the digital audio master clock, reducing the small variations in the timing of the digital signals
- A dedicated USB audio output that buffers the signal to purify the signal further
- EMI filter circuitry that removes interference from the USB output
By inputting a USB stream from your laptop/computer you can take particular advantage of the Detox circuitry removing noise. All incoming signals pass through the Detox system, whether USB, Ethernet, or Bluetooth, so the benefits are audible however you use the LINK.
Phase noise on the LINK output recorded on a signal integrity analyser
Power supplies are essential to energize circuits and make electronics work. However, if they are not implemented well, they can add noise and distortion. The LINK’s advanced digital processors are powered by an extremely low noise, multi-stage power circuit to enable them to achieve peak performance. It comes supplied with a low leakage medical grade DC power supply.
- Nine organic low resistance capacitors help filter and purify the power
- 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
- A triple linear regulated circuit purifies remaining noise
- Not all DACs require power from the USB input, so the LINK features a USB power switch for further noise suppression. The USB power feed is no longer active alongside the data line
SOLID ALUMINIUM CASE
It has long been understood that it’s a good idea to separate digital and analogue electronics. The LINK is a pure digital system housed in a thick CNC machined aluminum case preventing EMI transmission.
The LINK has been designed from the outset to be extremely low noise. No matter how well engineered, individual components will still emit EMI, creating crosstalk. To counter this Stack Audio have gone a step further using EMI absorbing materials placed in pockets inside the machined aluminium case above the EMI emitting components.
The LINK’s solid machined case dissipates air-borne vibrations throughout its mass.
The LINK features Stack Audio’s Advanced Vibration Dissipation Composite (AVDC) sandwiched in a pair of aluminum inserts which sit between the baseplate and the case, isolating vibration coming through the equipment rack.
FLEXIBLE, POWERFUL, INTUITIVE
For an audio company the complexity of developing a stand-alone software eco system is substantial and it has to be kept up to date with the ever-changing landscape of file-based media services.
By using Volumio as the foundation of the LINK’s operating system, Stack Audio is able to deliver a product that can work as you want it to: an audiophile USB hub; a UPnP or OpenHome endpoint; an AirPlay compatible or Chromecast player; a Roon endpoint . In simple terms the LINK enables you to choose.
DEDICATED FOR AUDIO
The LINK is a true hi-fi digital music player tailored to offer bit-perfect gapless playback and uncompromised audio quality. It handles multiple formats: MP3, FLAC, WAV, AAC, ALAC, DSD and supports DACs with MQA decoding (if your DAC supports MQA).
BIT PERFECT RIPPING
If you want to back-up and archive your CD collection without using a PC, simply plug in a USB CD drive and let the LINK manage the process for you.
The LINK is solid state with no moving parts, or vulnerable touch screens. It is built in the UK sharing production facilities with products for aerospace, medical and military applications.
The software team behind the LINK’s operating system are part of an avid developer community focused on the continual evolution of the system to deliver compatibility and flexibility in an ever-changing file-based media world.
CONTROL IT YOUR WAY
Control the LINK with a phone or tablet with the Stack Audio app, your favourite IOS or Android UPnP app, AirPlay or Roon. Alternatively use the HDMI output to connect to a monitor or touchscreen, or control it remotely from your PC through the Stack Audio web interface.
The LINK is a UPNP/DLNA device that supports music management and streaming apps like Roon, TIDAL and Spotify. It works with Apple AirPlay, Chromecast and Internet radio. You can control the LINK with any UPnP app or OpenHome control point.
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 playback
- The advanced clock circuitry re-clocks any USB input
Mechanical feature summary
- 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
Software Feature Summary
- Control via a smart devices and PC/laptop
- Control through the Stack Audio web interface
- Multi-room enabled
- Software has a large user base and is frequently updated
- Plug a USB CD drive in and rip your disks bit perfectly to your network or external storage
- Plug in a USB disk drive and access your stored music
- Support for TIDAL , Qobuz and internet radio (Shoutcast)
- Shairport-sync (apple compatibility)
- Roon ready (In progress)
- UPnP AV protocol with audio streaming extension (OpenHome)
- Gapless Playback
- On-Device Playlist
- MQA (only if DAC supports hardware unfolding)
Supported Audio File formats
- Lossless: DSF (DSD), DIFF (DSD), DoP (DSD)
- PCM Lossless: FLAC, Apple Lossless (ALAC), WAV, AIFF Compressed (lossy) Audio: MP3, AAC (in M4A container) MQA (only if DAC supports hardware unfolding)
- Finish : Available in anodised silver or black
- Dimensions: 174mm(W), 140mm (D), 25mm (H), 1kg (without external power supply)
- 2 x USB inputs
- 1 x USB B detox input
- Ethernet input
- 18v 1amp- 1.5amp DC input
- 1 x dedicated USB audio output
- HDMI output for connection to TV/video monitor/touch screens for control (not i2s)
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