DACs: USB vs. Coax. vs. Optical
Dec 12, 2007 at 6:46 PM Thread Starter Post #1 of 55

Operandi

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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?
 
Dec 12, 2007 at 6:59 PM Post #3 of 55

Operandi

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Quote:

Originally Posted by jh4db536 /img/forum/go_quote.gif
what if you had a laptop source with no optical or coaxial outs?


Well thats obviously USBs biggest strong point but my question wasn't hypothetical it was practical.

My comp has all thee options and I'm wondering which I should go with?
 
Dec 12, 2007 at 7:30 PM Post #4 of 55

Ross1

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Quote:

Originally Posted by Operandi /img/forum/go_quote.gif
Well thats obviously USBs biggest strong point but my question wasn't hypothetical it was practical.

My comp has all thee options and I'm wondering which I should go with?



Personally, I wouldnt go with USB, just from my experience. I have an EMU 0404 USB..... its sounds just fine through USB, but it simply takes longer to buffer, if you pause music (and more noticably video) for any length of time, it takes a while for it to kick in again after you press play.

Added to that....
E-MU Systems - Support

Yes, you read that right. Still no full driver support in vista for my EMU 0404 USB. Remember the product was released when there were beta copies of vista available. (I tried to use the beta drivers, and the program hanged when 'updating the firmware' of my EMU. If I turn off the soundcard when playing music through foobar, it crashes the whole PC and i have to restart!).

Im now using the optical out on my mobo, so thankfully i do not have to deal with EMU's downright awful driver support. I *think* it sounds a bit cleaner too, but maybe thats me wanting to see it as better.

From what I read, coaxial tends to have the least jitter, but over shorter distances optical can tend to be more accurate (under 5m...?)
 
Dec 12, 2007 at 7:34 PM Post #5 of 55

jh4db536

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Supposedly Coaxial is the best if your transport is good. I think it has something to do with a 2 way (feedback?) transmission deal and probably cable tweaks. The type with no solder joints in the end connectors.

Optical isolates the computer noise for sure. Supposedly more suspect to jitter artifacts (DAC1 has 'Ultralock' to deal with this). 1 way transmission. Cable is fragile and length is limited before quality degrades.

i personally use the optical out and i like it. Never tried the coaxial though since my sources don't have it except for my $50 dvd player.
 
Dec 12, 2007 at 7:48 PM Post #6 of 55

Riboge

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From what I've been a able to read and learn from my own experience the spdif--coax or toslink--quality depends mostly on the quality of the clocking and sampling at the computer end, which means the quality of the soundcard or motherboard source for it and for usb it depends mostly on the reclocking and/or other jitter reduction capabilities of the DAC. So which is preferrable aside from bandwidth follows from the specifics about these. Perhaps you can describe these in your case, so others can offer more specific comments. There are widely differing views on these things.

I have used two very good usb dacs--stello 220mkII and Bel Canto 3--with very good results. The latter, I believe, reclocks the signal entirely with its own superclock. Therefore you'd think it would be as good as spdif via a soundcard with great clock or via an empirical offramp using a superclock, but it isn't in my experience. The offramp sounds the best using Kernel streaming via foobar 0.8.3 and my Lnyx soundcard is a fairly close second using ASIO via foobar 0.9.5. Before I had these I ran spdif out of an X-Fi Extreme Music and found it slightly better 24/96 than USB 16/44.1 to the same DAC.
 
Dec 12, 2007 at 8:10 PM Post #7 of 55

Operandi

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Good info, thanks.

Right now I'm leaning towards the Firestone Spitfire which is optical and coax only.
 
Dec 12, 2007 at 8:13 PM Post #8 of 55

Operandi

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Quote:

Originally Posted by Riboge /img/forum/go_quote.gif
So which is preferrable aside from bandwidth follows from the specifics about these. Perhaps you can describe these in your case, so others can offer more specific comments. There are widely differing views on these things.


Sure, right now I'm using an nForce2 based AOpen board. The digital inputs and outputs are located on PCI bracket, not on the I/O panel (if that matters).
 
Dec 12, 2007 at 8:47 PM Post #9 of 55

mchang

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Can you translate for the layperson? Do the above improvements of coaxial and optical equal a noticeably better sound over USB?

I just got the 0404 USB, and am using it through USB. I haven't noticed the delays Ross1 mentioned (but I haven't been looking/listening for it). Should I run out and get a mini-jack-to-optical cable?
 
Dec 12, 2007 at 10:45 PM Post #11 of 55

LeonvB

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Quote:

Is there any reason to opt for the USB interface?


Convenience. You don't need a sound card, you can plug it in in about any half decent computer.
Jitter. Most good DACs like a Stello 220MKII reclock their input signal, so no problem there.
Price of interconnects. A USB 2.0 cable isn't expensive at all, and longer interconnects aren't a problem (up to 5m before you need a repeater).

Some people claim USB DACs can stop working every now and then due to USB transmission problems, but I've not heard a single issue during hunderds of hours of listening to it.
 
Dec 12, 2007 at 11:52 PM Post #14 of 55

sejarzo

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Quote:

Originally Posted by mchang /img/forum/go_quote.gif
Can you translate for the layperson? Do the above improvements of coaxial and optical equal a noticeably better sound over USB??


If one is referring to a standard "USB Audio Device" that runs "driverless" (meaning, it is recognized by the OS and operates via the functionality built into the OS) then it is a "qualified maybe"......depending on the implementation of the USB receiver, etc.

Quote:

Originally Posted by mchang /img/forum/go_quote.gif
I just got the 0404 USB, and am using it through USB. I haven't noticed the delays Ross1 mentioned (but I haven't been looking/listening for it). Should I run out and get a mini-jack-to-optical cable?


IMHO, absolutely not!!!

The 0404 USB does not operate as a standard USB audio device. Instead, the data stream is sent via an entirely different method ("block mode") over the USB interface, and the data is then reclocked out of a buffer in the external unit to the D/A conversion circuitry. That's why you need to install the E-MU drivers to make it work--it really is a more elegant solution than the standard USB audio device system.

If you don't notice a problem, that's even more reason to stick with your current set-up. Personally, on XP, I have not noticed any issues unless I try to copy huge FLAC's from my desktop's internal drive to the external USB drive while I'm listening via Foobar>ASIO>0404 USB.......and then there only might be a glitch once in a while.
 
Dec 12, 2007 at 11:55 PM Post #15 of 55

Penchum

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I can think of no reason to go USB when you have the other two available, unless portability is a must. I use optical from my X-FI music to my DAC, and it works great. Also, from my notebooks built in optical. Several pluses I have noticed. Optical cables generally weigh less, they are easy to connect, more and more equipment is turning up with optical as a choice. Lastly, they don't cost very much for a good quality cable made to the length you need.
Happy hunting either way!!
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