In the quest for a quality digital audio file server we next tried the Sonos Zone Player and the Sonos remote controller. Since we wanted only digital output we did not need the Zone controller with a built-in amplifier. The output was to be directed to an ADC contained within a Mark Levinson CD player. The player has coaxial SPDIF input and the Sonos has SFDIF coaxial output so it seemed like a perfect match.
The Sonos does not store audio files, it merely receives a digital stream through the network and outputs to the stereo system. The Mark Levinson DAC has the best Burr Brown (Texas Instruments) device available a few years ago. Before the digital data is sent to the DAC, it is re-clocked to eliminate jitter.
What could go wrong, all we needed was a decent digital audio stream for the Mk. Lev to do its job?
We installed the Sonos and listened to some CDs that we know very well. We compared the sound of the Sonos to direct playing of CDs on the Mark Levinson CD player as well as playing through a $29 Turtle Beach USB sound card and through an Airport express. Itunes sucks for streaming to the Airport so we used Media Monkey together with Airfoil.
Our highly subjective opinion was that the $29 Turtle Beach sound card connected to a notebook computer with Toslink to the Mk Lev was the best sound. Next was the Airport via Media Monkey and Airfoil. Why did the Sonos not sound as good? We are talking about a digital stream that is being re-clocked by the Mark Levinson?
Before losing interest in this thread please consider that we did find an excellent solution to the digital file serving goal. For about $280 anyone could duplicate this system and produce results limited in quality only by the stereo to which you connect it.
My interest here is the hope that a reader will offer some suggestion as to why the Sonos does not sound as good as it should. Our evaluation was quite subjective but we used methods that we feel are appropriate for comparing realism and quality of recorded audio. We know that the Mark Levinson components connected to a dedicated 30-amp circuit can handle just about any music thrown at them. The B&W speakers are difficult to beat. Excellent recordings sound like excellent music on this system.
We chose familiar recordings and paid attention to a limited set of specific effects, comparing the sound when played from the CD to the sound when played from other sources. Out principle test CD was Leonard Bernstein's Final Concert. This is an excellent recording of Benjamin Britton's "Sea Pieces" and Beethoven's 7th Symphony. Both pieces cover the full range of dynamics and musical complexity. Subtle effects mix with substantial orchestral background in both pieces. The recording is clear and does not seem overly edited. There is a fair amount of "live performance" noise that was not edited out including grunts and groans from Bernstein, baton clicks and coughs from the audience. Listening to the recording under the best circumstances,one has the impression of a live performance, nothing distracts from that impression. Played through the Sonos (WAV file ripped to hard drive), the performance lacks this feel. In addition to a general impression, we concentrated on a few specific effects which we feel correlate with the impression of a live performance. Strangely enough a few of the most indicative effects were what most would consider defects. Bernstein's moaning and occasional baton clicks, sit on top of a full orchestra. In the best circumstances, they sound like what they are. In less than ideal circumstances, they are unidentifiable noise that confuses the brain. To us, it is better to have a clearly identifiable sound than a confusing noise that distracts you from the music.
We did not concentrate on just the noise, we also listened to a few specific instruments. Flute seems to be a good indicator of musical accuracy. Plucked violin strings are another good test sound. We could hear clear indications of instrument character and clarity in complex contexts when everything was working well and less than this in other cases. It is certainly possible that jitter could mask these subtle effects but the Mark Levison is re-clocking the digital stream. Why does the final solution (to be announced in a future post) sound so good but the Sonos doesn't? Why does the $29 Turtle Beach USB sound card sound better? And why does the final solution (to be announced soon) sound soooooooooooooooo good?