Assuming fixed DAC/analog components,Im only aware of 2 parameters that can affect the sound of a a digital playback system : a) data accuracy b) jitter Since a is not an issue a sanely constructed system, then it must be b: jitter This is where Digital meets the realms of the real world same Bit for Bit accurate Data but very different sound between Transports and even Interlink cables: so what?? Lowest Jitter will not always guarantee best audio performance (It very much depends on what happens down steam at the DAC) its the distribution (signal content) of the Phase Noise that is critical, types of Phase Noise that are always detrimental :- A. Data correlated artifacts. These are signals or spurie within the Phase Noise plots that are directly correlated to the Data processing
B. Fixed frequency Non Data correlated discrete artifacts, such as mains hum, non synchronies Front panel displays & MCUs etc. Its generally accepted that the SPDIF standard is poorly conceived as the Master Clock is located within the CD transport section or in the PC (where Jitter) is unimportant), where as the DAC which is extremely Jitter sensitive is fed from a Recovered clock which is buried within the SPDIF Data Stream. To make matters worse, no attempt has been made to de-correlate or randomize the SPDIF Data during transmission, so that the clock recovered by SPDIF receiver is guaranteed to be heavily contaminated by Data correlated Phase Noise Jitter of the very worst kind. The "evil brother" of SPDIF, AES-EBU, is pretty much the same, the only difference being that it is balanced 110ohms. A guaranteed a solution to the deficiencies of SPDIF is to design the DAC as the Master clock device i.e. a low phase noise clock located next the to DAC and send the clock back to the transport via a second connection preferably optical for best isolation. Arcam, Pink Triangle, Wadia, EMMLabs use this method. As mentioned earlier, nor transport neither PC (or squeezebox, for that matter)is sensitive to clock jitter, so no particular care need be taken for this second link. If designed and implemented correctly, this method guarantees that the DAC operates from the lowest Phase Noise clock with no PLLs in the signal path or whatsever. In this scheme of thingsToslink works best as gives galvanic insulation and protects from other forms of jitter (from RF or PS) to reach the DAC. So from an audiophile standpont, a squeezebox with world clock input-and toslink output, would be warmly welcomed, and 24/192 capability would let experiment upsampling algorithms and stay future-proof.i Of course you should have a DAC with the masterclock inside, but in that case you'd be very close to perfection. Cheers, Betto -- betto ------------------------------------------------------------------------ betto's Profile: http://forums.slimdevices.com/member.php?userid=13315 View this thread: http://forums.slimdevices.com/showthread.php?t=38637
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