PS Audio Bridge II Plug-In Card for DirectStream DAC

MQA Unfolding Comes to the DirectStream DAC

Equipment report
Digital-to-analog converters,
Music servers and computer audio
PS Audio DirectStream DAC
PS Audio Bridge II Plug-In Card for DirectStream DAC

PS Audio recently updated the software for its Bridge II card to enable it to “unfold” MQA files. The Bridge II card is an accessory that plugs into a slot in the rear of the DAC to add additional capabilities. Originally, the Bridge II enabled the DirectStream DAC to connect to a home network where digital music files are stored and to play those files, turning the DirectStream DAC into a machine capable of handling PCM files up to 192kHz and DSD64 files. Like all PS Audio software updates, the update to software for the Bridge II is free for downloads, and priced at $25 for a copy on an SD card. To implement the software upgrade, insert the SD card in a slot in the back of the DAC, turn on the DAC, and the software is updated as part of the boot-up process. The Bridge II card sells for $899.

The latest Bridge II card “unfolds” MQA-encoded files. Unfolding is the first decoding step in MQA, converting the file from 48kHz to the file’s original sampling frequency. It is not, however, the full MQA decoding. PS Audio was able to achieve this modification with a firmware change, rather than via a modification of its hardware. After the MQA signal is unfolded, the DirectStream DAC treats it like any other PCM signal: It converts it to DSD, upsamples it to 20X DSD, then downconverts it to 2X DSD, which is run through a final filter that is only 24dB/octave, unlike some of much steeper brickwall PCM filters. Bill Leebens, PS Audio’s Director of Marketing, told me the MQA playback upgrade will work on “all DirectStream Junior (DSJ) DACs and any DirectStream or older Perfect Wave DACs that have the optional Bridge II installed.”

In addition, the Bridge II card is now Roon-ready, so if you share my enthusiasm for that playback software, you’ll find it also works fine on the Bridge II. Not a Rooniac? Then you can try an app called MConnect Control, which plays back music files and is free. It also lets you stream Tidal, and decodes Tidal-streamed MQA files. Unfortunately, MConnect Control is less intuitive than most other remote apps I’ve tried.

I was most curious about how well PS Audio’s solution to MQA worked. Would it sound good or would all the additional processing the DirectStream DAC imposes on PCM signals degrade MQA? So I obtained a review sample and checked it out.

Installation and Use of the Bridge II Card
The Bridge II card came in a small box with printed instructions for installation. Following the instructions carefully, I installed the card in my personal DirectStream DAC. Even for a klutz like me, it was straightforward. I then inserted an SD card, which updated the operating system to handle the Bridge II, and turned on the DAC. It read the card, changed the software, and in less than a minute, was ready to play. Physical hook-up amounted to nothing more than plugging a network cable into the RJ45 jack.

I made sure my Roon server (a laptop computer dedicated to music playback, located in my office) was turned on and running Roon, and selected the PS Audio DirectStream DAC as the audio-output device. I gave the audio zone a name: PS Audio Bridge for future reference. With the Roon Server ready, I needed to change the iPad I use as the Roon remote control. I fired up the iPad, launched the Roon remote app, selected the PS Audio Bridge as the output on the iPad, and voîlà, I could play music using the familiar and easy Roon environment—it looked just like Roon always does, so no learning curve. I played a few albums to start breaking in the Bridge II (it takes two days’ break-in) and to be sure everything was working.

I also tried the recommended alternate remote-control program, MConnect Control. In this job as reviewer, I get to use lots of different remote-control apps for my iPad. A few are great, most good, some just ok, and a few desperately need help. MConnect Control would fall in the ok category—functional, but not intuitive or easy to use. But it’s free, which will appeal to those who balk at the tariff for Roon. Needless to say, I did most of my listening evaluations with Roon.

The DAC’s normal inputs are still functional; however, signals received at these inputs weren’t MQA-unfolded; only inputs received over the network via the Bridge II can enjoy MQA unfolding.