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Why USB to SPDIF and not optical?

Using a Mac Mini as my music server, and was wondering why the sound would be better converting the USB to SPDIF to my Bel Canto Dac3 as opposed to just hooking up a mini to Toslink? If there is a valid reason, what is a less expensive alternative to the Bel Canto USB Link?
lgoler
audioengr
3,282 posts
 
Just improving the Toslink from the Mac will reduce jitter a little, but it does not change the clock inside the MAc, which is the true source of the jitter.

If you go USB to S/PDIF, there are three advantages:

1) Eliminate the Toslink optical conversions as a source of jitter
2) Establish a new low-jitter clock to replace the one in the Mac
3) Output from S/PDIF coax to the DAC, whic has the opportunity to have lower jitter than the Toslink (depending on implementation)

BTW, this can still give you galvanic isolation (just like the optical) providing the converter is properly transfomer coupled.

Steve N.
Empirical Audio
lgoler's avatar
lgoler OP
55 posts
 
Steve,

Since you seem to be an expert in "jitter", can you provide a link to any qualitative data explaining this phenomenon, in layman's terms?

Lance
objective1
95 posts
 
I just spoke with the folks @ Bel Canto...

and they essentially mirrored Steve's comments

(not that i didn't believe you Steve... i just didn't know you had responded :-) )

I asked why i'd want this 24/96 doohickey if i already had a Dac3 and a 24/96 toslink connection from my computer to the Dac3.

First (according to Bel Canto) the usb->spdif conversion in the 24/96 link is a better implementation than the one already in the Dac3 (plus the fact that the usb input doesn't do 24/96).

Secondly, he believed the optical Toslink from the computer didn't perform as well as the usb anyway.

So that's the retransmission of my conversation this afternoon.. :-) Enough for me to try one..

Happy listening
dtc's avatar
dtc
1,047 posts
 
I am a little concerned about the statement that it is compatible with native Windows drivers. Do you know how the Link product interacts with XP's audio subsystem? The literature says it accepts 24/96 but I think parts of the XP subsystem probably needs to be bypassed to get 24/96 cleanly through the OS. So does it have drivers that bypass KMixer and the like and will any software product (iTunes for me) work with it directly or do you need special drives (like ASIO) to use it? Any information would be useful.
dtc's avatar
dtc
1,047 posts
 
In addition, XP generally upscales 44.1 files to 48 unless special drives are installed. Does the 24/96 link help with that problem?
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