DACs: USB vs. Coax. vs. Optical
Dec 14, 2007 at 4:59 AM Post #47 of 55
im sure someone can provide a more technical explaination. but basically spdif is just another way of outputting a digital signal to your dac. Its a format developed by sony and phillips hence the first sp. Its not really a hybrid of either, just another format.
 
Dec 14, 2007 at 5:29 AM Post #48 of 55
Quote:

Originally Posted by Cata1yst /img/forum/go_quote.gif
wait S/PDIF is kinda like a hybird between coax and optical? so i can use either or cable as long as im outputing SPDIF and receiving it?
(pardon the n00bie question)



S/PDIF is just a type of digital audio, like AES. Coaxial and Optical transport S/PDIF.
 
Dec 15, 2007 at 6:10 AM Post #49 of 55
Quote:

Originally Posted by Operandi /img/forum/go_quote.gif
I'm in the process of researching a DAC for my desktop audio system. My PC has all three options open. Aside from optical and coax allowing for more bandwidth (24bit/96khz) what are the factors in deciding what to use? Is there any reason to opt for the USB interface?


It's better to ask "Are there any reasons to use anything else, like coax or optical?". Yes, you have to have more input options if you are going to use some more transports, like CDP.

But, if you would use PC as the only transport then USB is the best option - universal, almost error-free and COMPLETELY protected of incoming jitter. With regards to incoming noise via USB: it is a matter of ext.DAC implementation, not the trouble of interface itself. It is quite easy to avoid any bus noise influence to resulting analog signal. So I believe that only the minority of the cheapest ext.USB DACs are affected by bus noise.

To get the basic knowledge on the subject, I recommend to read Computer-Driven Audio - Is it Superior to Optical-Based CD Playback?.
 
Dec 15, 2007 at 10:58 AM Post #50 of 55
Quote:

Originally Posted by Penchum /img/forum/go_quote.gif
Hey, I'm just curious. I can't rememeber what others were worried about some time back...Was there ever an issue with bus noise for USB? Or was it something about the chip that translates USB into SPDIF? Thanks!


There was an issue with bus noise with the Corda Move for some. It all depends on the PC, for many its not an issue.
 
Dec 15, 2007 at 11:15 AM Post #51 of 55
I personally would use optical S/PDIF.
For one simple reason. The computer and DAC are electrically isolated from each other, with the benefits this gives when it comes to noise level.
 
Dec 15, 2007 at 12:53 PM Post #53 of 55
Quote:

Originally Posted by krmathis /img/forum/go_quote.gif
I personally would use optical S/PDIF.
For one simple reason. The computer and DAC are electrically isolated from each other, with the benefits this gives when it comes to noise level.



This is what I thought too. Also, if a person's notebook already has optical out, it seems like it should at least be tried to see how good it is.
smily_headphones1.gif
 
Dec 15, 2007 at 2:37 PM Post #54 of 55
Quote:

Originally Posted by Penchum /img/forum/go_quote.gif
This is what I thought too. Also, if a person's notebook already has optical out, it seems like it should at least be tried to see how good it is.
smily_headphones1.gif



This is true, if your DAC allows the option of both, it should be cheap to compare. The Pico doesn't even convert to S/PDIF from USB?
 
Dec 29, 2012 at 8:52 AM Post #55 of 55
I have a Schiit Bifrost, and have the same questions in this thread. Here's a response I got from another forum regarding USB vs fiber:

"[size=small]No you're using a short run so the advantages of fiber at the bandwidth audio requires and the the length negate the cost of fiber.[/size]
[size=small] If you run through digital fiber you're adding other components to the chain too. USB will stream the digital signal from the playback application through the OS's audio handling coding then into the DAC which decodes it and converts it to analog.[/size]

[size=small] With Fiber you run through the OS's coding into the sound card through it's digital to digital conversion through fiber to the DAC which then performs the digital to analog conversion.[/size]

[size=small] The other thing to consider is that when going through the optical you are adding another clock to the signal, USB will rely on the original clock from the OS. Reclocking a signal can lead to conversion errors as well.[/size]

[size=small] I'd be surprised if you honestly got a noticeably different sound between any of the sources, but I would hate to see someone spend money on a cable when there is a simpler way with the same performance.[/size]

[size=small] Schiit put a lot of time and money into the development of their USB interface, it's top notch."[/size]

[size=small]  [/size]

[size=small] The guys at Schiit Audio are partial to coax and fiber:[/size]

[size=small]  [/size]

"Well then, how about your USB? Is it fully buzzword compliant? 24/192? Async?
It is absolutely buzzword compliant! Not only is it USB async, but it’s USB 2.0 async that’ll do up to 24 bits/192 kHz sampling rates. Yes. USB 2.0. Not antique 1.1. It works without drivers on Mac and we provide drivers for Windows 8, 7, Vista, and XP. It’s a good-sounding, reliable, solid implementation of USB. But that’s like saying, “Well, its a very nice meal, given that the chef could only work with McDonald’s hamburgers.”*
 
Wait. Are you saying USB is crap?
We’re saying we put a ton of time into our USB implementation, but, to our ears, USB still doesn’t quite offer the performance of SPDIF. And we can even get into shades of gray on SPDIF too: consider Mike Moffat’s AT&T ST-optical interfaces and Sumo’s Axiom/Theorem transport and D/A, which had a separate low-jitter master clock connection from the transport.
 
So how do I get some of this SPDIF stuff?
If you have a Windows desktop, most decent sound cards and many motherboards have SPDIF coax or optical. If you have a Mac, almost all of them have SPDIF optical output buried in the headphone jack. If you have a PC laptop, well, hey, then things can get a lot more complicated. That’s why we included a USB option."
 
Source: http://schiit.com/schiit-faq/about-bifrost/
 
So, with all these varying opinions, I think the best thing one can do is just to try all the options and then see what YOU think is best. Until we see some actual tests done with the proper equipment/tools, it will all be speculation or opinion. That's just my two cents :)
 
Cheers
 

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