NAS, player

We're nearing the end of this series and before it's over I promise to figure out how to make a diagram of the whole network music system for you. Yesterday we covered the controller, the one piece of the three parts to a DLNA music system: server, controller, player, that many of us are familiar with. The controller connects the user to the system and presents information of what's in the library, and provides a means of selecting and playing tracks. From a designer's standpoint, the last piece of this DLNA puzzle is by far the hardest to design, most important when it comes to sound quality. The player. Servers and controllers in this system have little impact on how the system sounds–if any. But the player, the one that connects to your DAC, is critical. In the PS Audio system we rely on a device called the Network Bridge. A PC board with a computer and Digital Lens built into it that slides into the rear of the DAC and serves as another input. In other DLNA systems, like Linn's and Naim's offerings, a similar arrangement of internal computer is built in to their DACs. Still other players (renderers) are external and there are a fine crop of them, including the Sonore Rendu, Aurender N100H, Auralic Aries, among others. These devices are all similar in what they do, which is a lot. The player is by far the most complex device in the entire chain. Not only does it have to take files and configure them for a DAC, it also has to decode many of them. For example, when you see that a device can play the following file types:

• AAC
• AIFF
• ALAC
• APE
• DIFF
• DSF
• FLAC
• MP3
• OGG
• WAV
• WV
• WMA

With few exceptions, each of these file types has to have a separate program to decode it, prep it for delivery, do what designers think best to get rid of jitter and help it sound good, all before sending it to the DAC. It's a big deal, and the skill of the designer and programmer for the player has everything to do with how it will end up sounding. DACs can take audio in only one way. I²S. I²S is the internal format of all DACs and has separate clocks and data on multiple lines. When your transport outputs digital audio through TOSLINK, Coax, or XLR, it is sent with only a few wires. All the many separate clocks and data are mushed together into a single stream in a format invented by Sony and Philips years ago, called S/PDIF (Sony Philips Digital Interface). A DAC does not know what to do with S/PDIF and there's an input circuit that tears this stream into its component parts, I²S, before presenting it to the DAC. External network players are no different. Once they're finished with processing and decoding the music streamed to them, they too wind up with I²S. They then also mush I²S together into a single stream to send to your DAC, which (of course) then undoes all their work and we get I²S again. (and yes, there's always some quality lost in the process–just like with USB). Some devices, like the PS Audio Bridge, Linn and Naim's internal streamers, output only I²S - which is the advantage of built in streaming. A few external devices, like Sonore's Rendu, use a protocol invented by PS Audio Engineering and distributed freely to the Audiophile manufacturing community, that takes advantage of HDMI's superior connectors and cables to deliver I²S directly to DACs that can accept it. Tomorrow we'll start to wrap up our series on NAS.