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"Once we rolled our sleeves up and figured out some of what's going on, we decided to add a Digital Lens inside the Bridge to make it truly asynchronous - which basically decouples everything from any system-related clock. Furthermore the Lens stores and rebuilds the digital audio data and then resends the new version out via I²S to the DAC. I like to imagine the Lens in the Bridge as a Power Plant. The idea behind a Power Plant is simple. It needn't matter what the power quality coming in is if you take that power, convert it to DC and then regenerate new AC. In the same way we take whatever is fed down the network into the Bridge, handle all the conversions and processing needed and then store the end result in a memory buffer. An external low-jitter unrelated clock then spits that rebuilt data out to the DAC and whatever is happening on the network or in the Bridge isn't related to what you're actually listening to, thus realizing the dream of making the delivery system irrelevant."


Why is I²S superior to S/PDIF? For travel along S/PDIF roadways, musical data and its associated clock information are packaged together in series. The clock data must later be extracted via a process that could ungenerously be referred to as 'best guess'. S/PDIF digital audio transmission is therefore more prone to input timing errors (jitter). I²S or parallel/separate transmission of music data and clock is why more technically-minded digital audiophiles dismiss S/PDIF as a not-quite-good-enough transmission method. I²S makes them salivate. I can understand why.

Initially designed for short distance connections inside the same box—i.e. many mainstream CD players—I²S transmission keeps audio data and the timing of that audio data (the clock) separate as they are moved from transport (Network Bridge or PWT) to decoder (PWD). In the case of the PWD that's a Wolfson 8740 chipset doing the heavy lifting. Users of the PWT/PWD combo have their boxes’ umbilically I²S linked by an HDMI cable. Inserted directly into the backside of the PWD itself, the Bridge's I²S connectivity is internalised.

An early exit for the cat from the bag. The PWD sounds more engaging, more wholesome when fed ones and zeroes via the Network Bridge (and presumably PWT) than it does as standalone DAC, USB- or S/PDIF-connected unit to PC, Mac or streaming device (Sonos/Squeezebox). Specifically a 24/88.2 SACD rip of Kraftwerk's Minimum Maximum is possibly the most single most jaw-droppingly tangible sound I've heard from any source in my listening space. I chose the word 'tangible' with careful deliberation. This is music that invites the listener to reach out and touch it. Turning my words in on themselves, the PWD + Network Bridge itself is the sound of a careful liberation.

“The Sophtware Slump”. Having spent over six years as an avid Squeezebox user/fan, its supporting software ecosystem is—for this user—too accomplished to quit overnight. Over eight years of open-sourced community development means Squeezebox Server is one slick number. Its completeness in library management and accessibility is why I run Squeezeslave (a Squeezebox emulator) on top of OS X despite having dispensed with the attendant hardware. Yes the Squeezebox Touch offers tremendous zip and zing to digital audio newcomers but in the company of more luxurious ancillaries its nylon transport pants are bettered by silkier $1000 CD players. Remaining a strict digital front ender, I’ve found a MacMini + Audiophilleo (or JKSPDIF) to be a better sounding transport than the Squeezebox Touch.

In the emulation world Squeezebox Server sees Squeezeslave as a client and streams music to it, which in turn pushes the audio ones and zeroes onto a USB-connected Audiophilleo or JKSPDIF. I browse, search and play albums via Squeezebox Server's web interface (when sat at my work desk) or use either iPeng or Squeezepad on an iOS device (when sat on the couch). Squeezeslave is my daily runaround but it's Redbook only. I am thus obliged to take the more luxurious Audirvana out on leisurely Sunday trips when the hi-res mistress comes a callin'. Two cars to drive.


Moving over from Squeezebox Server (and Audirvana) to PS Audio’s Network Bridge involved a number of weeks in the realm of Universal Plug’n’Play. UPnP is the protocol that underpins the PS Audio streaming experience. Although a common streaming protocol used by everyone from Western Digital to Linn, this was my first exposure to what is generally considered the definitive household network streaming dialectic. There are three key terms that the interested parties should first grasp: media renderer, media server and control point.

The media server is the host computer upon which the music is stored. A UPnP server application (eLyric Music Manager, Twonky etc.) is installed on the media server so that music is ‘served’ to the media renderer that requests it. In this case the media renderer is the Network Bridge. The control point (eLyric iOS app, Linn Kinsky) is the spark that ignites the conversation between media server and media renderer. Here we find the third corner stone of the media streaming system devilishly labeled user experience. The control point is where music selection and playback is exacted.


Basic playback functions (pause/play, next/previous, volume) and PWD-specific options (digital filter selection, upsampling and source selection) can be controlled by way of the PWD's inviting little touch screen and/or supplied remote control. The screen also glows with artist and song title text and that all-important cover art as the last vestige of a tangible music format. (Note: cover art screen display requires the user to insert an SD card into a slot in the rear of the PWD hitherto used to upgrade DAC firmware.)


The music library can't be browsed from the touch screen. Instead a desktop app (Linn Kinsky) and/or PS Audio’s own iOS app is required. In the absence of a specific desktop (control point) app from PS Audio, I turned to Linn's Kinsky. Developed for the Linn range of music players, Kinsky integrated flawlessly with my MacMini/eLyric Music Manager and NB+PWD media renderer.  Its interface is clean and very responsive (i.e. no lag) but there's no music search function. The user is left to browse the music collection via artist, album or folder. Kinsky provides some basic control options for the computer-bound user. Two drawbacks though - 1) the play/pause button in Kinsky doesn't play/pause the NB but acts as a ‘next track’ button and 2) Kinsky won't auto-detect a playlist initiated by iOS eLyric.

Down on the couch PS Audio's eLyric iOS (iPhone/iPad) apps will each run you ten bucks but they take the control point game up several gears with superior handling and broader functionality. Upon first launch of either iOS app, the media server and media renderer must be selected. Only then can the music library can be browsed by artist, album, artist/album and—my favourite—folder. It has taken me years of diligence and self-discipline to house each album in its own folder so browsing via artist only reminds me of how very many electronic/DJ mixes lie deep within. 14 Iced Bears? 16 Bit Lolitas? Nope, me neither. (I blame John Digweed). I circumvent these anomalies by folder browsing. If I'm after a specific artist or album only then do I send in the search dogs.