[Destroysall]

Hi all! 
 
I had a question concerning the two signal transports, Digital Coaxial and USB.  I am not sure which part of the forums this thread should truly be categorized under, but I posted here in the "Computer Audio" forum due to my question concerning the Digital Coaxial output on my PC's motherboard.  Moderators, please feel free to move this if necessary.
 
Any who, my question is what are the pros and cons of both outputs?  I have always used USB, but I am considering upgrading my DAC with the Schiit Audio Bifrost and have considered using it with my PCs motherboard via Digital Coaxial.  Is there any sonic differences in using Coaxial rather than USB?  I've done some research on this and some say DIgital Coaxial (S/PDIF, I believe) can be much more superior than USB (correct me if I'm wrong).  If this is true, it would be great news as I wouldn't have to spend the extra money to get the Schiit Bifrost with a USB output (unless I upgrade to a Mac).
 
So any info on this would be much appreciated, thanks in advance!
~Destroysall

 

[PleasantSounds]

Quote:

Hi all! 
 
I had a question concerning the two signal transports, Digital Coaxial and USB.  I am not sure which part of the forums this thread should truly be categorized under, but I posted here in the "Computer Audio" forum due to my question concerning the Digital Coaxial output on my PC's motherboard.  Moderators, please feel free to move this if necessary.
 
Any who, my question is what are the pros and cons of both outputs?  I have always used USB, but I am considering upgrading my DAC with the Schiit Audio Bifrost and have considered using it with my PCs motherboard via Digital Coaxial.  Is there any sonic differences in using Coaxial rather than USB.  I've done some research on this and some say DIgital Coaxial (S/PDIF, I believe) can be much more superior than USB (correct me if I'm wrong).  If this is true, it would be great news as I wouldn't have to spend the extra money to get the Schiit Bifrost with a USB output (unless I upgrade to a Mac).
 
So any info on this would be much appreciated, thanks in advance!
~Destroysall

 
This is a frequent topic around here, albeit I know first hand that finding anything useful in search results is an art that only a few have mastered, so I'll make it easy for you and provide the only true and valid answer: it depends
 
On the surface one could think that it doesn't matter: it's the same digital information passed between the PC and the DAC, so whichever way it gets there, the DAC has to chew through the same stream of zeros and ones. But it turns out that there is a difference. 
 
The SPDIF is a dedicated, specialised standard for passing digital audio signals between devices, while USB is an universal data transfer interface. So the specialised protocol should be better than the universal one, right? Well - read on...
 
At this point the respected reader of this message probably should reach for a stiff drink, as we're about to get really technical. If the technical staff doesn't scare you, then pour yourself one anyway to level with me, as I'm enjoying one right now
 
Ready? Here we go...
 
For the digital signal to be properly converted to analog, it needs to be fed to the converter (DAC) in precisely timed intervals, which correspond to the sampling rate of the digital audio file. If the timing is off, it will manifest itself on the analog side as jitter, noise and distortions. How to avoid or at least minimize these nasty effects? The answer is... no - this time there is a straight answer: make sure that the clock used for this timing is as precise as possible. But there is one problem with that: precision is expensive...
 
So how does this all affect our little dillema of choosing one digital interface over the other? As it turns out, these two ways of passing the signal differ in one quite significant detail: SPDIF passes the data already timed at the source, while USB leaves that responsibility to the receiver. 
 
Now those who haven't finished the drink yet should still be able to draw their own conclusion, but I'm on the second one already so I can't resist to offer my own: if your signal source has a better clock than the DAC device, then using SPDIF may indeed result in a better quality output. The problem is that more often than not, the devices we use as sources have very cheap (read: inaccurate) clocks. The onboard sound modules that most PC motherboards offer are notoriously bad, similar story with CD players where this type of connectivity is usually considered just a tick on the marketing blurb.
 
On the other hand, if someone builds and sells a dedicated DAC, they do understand that the only justification of its existence is quality. Motherboards already have DACs, so if you're going to buy one it's only because what your PC offers is not good enough. So when direct comparison is not possible, I'd bet that the receiver (DAC) will do a better job timing the data stream than the sender (motherboard of your PC).

 

[Destroysall]

Wow, as if this can't get more complicated already. LOL  Thanks for taking the time explain that, PleasantSounds.  That really made a lot of sense.  I did have a few more questions though.  My first one being how does Digital Coaxial compare to Digital Optical (TOSLINK)?  Are there any differences there or are they just the same thing?   My other question is would Digital Coaxial work fine if using the DAC in conjunction with the PURE i-20?  I see many Head-Fi'ers use this device in their rigs, so I question if it does really work.

 

[ROBSCIX]

Quote:

Hi all! 
 
I had a question concerning the two signal transports, Digital Coaxial and USB.  I am not sure which part of the forums this thread should truly be categorized under, but I posted here in the "Computer Audio" forum due to my question concerning the Digital Coaxial output on my PC's motherboard.  Moderators, please feel free to move this if necessary.
 
Any who, my question is what are the pros and cons of both outputs?  I have always used USB, but I am considering upgrading my DAC with the Schiit Audio Bifrost and have considered using it with my PCs motherboard via Digital Coaxial.  Is there any sonic differences in using Coaxial rather than USB?  I've done some research on this and some say DIgital Coaxial (S/PDIF, I believe) can be much more superior than USB (correct me if I'm wrong).  If this is true, it would be great news as I wouldn't have to spend the extra money to get the Schiit Bifrost with a USB output (unless I upgrade to a Mac).
 
So any info on this would be much appreciated, thanks in advance!
~Destroysall

 
A simple answer is, it depends.
At their base, the 3 are all different connection methods, so it depends on the quality of the receiver circuitry and the implementation.
 
I have never heard anybody suggest or prove that S/Pdif is superior over USB, as it depends which device in what context.etc. 
Newer DAC's such as the BiFrost, utilize Asynchronous USB transfer, which basically makes it immune to the same types of errors and timing issues that is prevalent S/Pdif connection types.
 
I have built many digital transfer systems, Coaxial, Optical, USB and have found that one is never always better in comparison to the others, it depends on the implementation of the circuit.
Some have great Coaxial inputs, some have better optical inputs, some have better USB inputs.
 
I would say read some reviews and talk to the owners of the BiFrost, great thing about it is you don;t have to buy the USB circuit and can add it later if you want to.
 
As for the Coaxial to optical, again it depends on the receiver circuits.

 

[PleasantSounds]

Quote:

Wow, as if this can't get more complicated already. LOL  Thanks for taking the time explain that, PleasantSounds.  That really made a lot of sense.  I did have a few more questions though.  My first one being how does Digital Coaxial compare to Digital Optical (TOSLINK)?  Are there any differences there or are they just the same thing?   My other question is would Digital Coaxial work fine if using the DAC in conjunction with the PURE i-20?  I see many Head-Fi'ers use this device in their rigs, so I question if it does really work.

 
In my opinion PURE i-20 is a perfect signal source for a DAC. If you compare what you get out of it with amplifying analog signal straight from the iPhone, you'll never listen to music direct from the iPhone again. The whole debacle USB vs. Toslink vs. Coax is insignificant, if you put it against digital vs. analog output from the iPhone.
 
Regarding Toslink vs. Coax - in ideal conditions they are the same. But this world being somewhat less than perfect, you may encounter differences. As ROBSCIX said: which one is better - it depends.
 
Both connections start with exactly the same signal, and if all goes well they both end with the same signal too. The question is what happens in between.
 
Coax is just a wire between the sender and receiver. It is simple but vulnerable, especially if the cable is long. Electrical cables tend to work like aerials: they pick up all the electromagnetic signals in the surrounds. The longer the cable, the bigger the chance of catching some radio stations, powerlines hum etc. Combine that with the signal getting weaker when the cable gets longer and your receiver (DAC) has a really tough job interpreting the garble that comes through. So if you go for Coax, my advice is use the shortest cable you can (less than 2m is rarely a problem). 
 
Toslink is a bit more complicated: it uses fibreoptical connection between the two devices, so the electrical signal needs to be first converted to light impuleses at the source, and then decoded back to electrical at the receiver. Technologically not a big deal, but it introduces more components in the chain (i.e. more things to go wrong). The fibreoptics are much better over long distances, are totally immune to all the electromagnetic interferences, but the cable itself is more fragile - in particular it doesn't tolerate sharp bends, kinks etc. The side benefit is also that the two devices are electrically decoupled, so the connection is not going to introduce the dreaded power frequency hum that plagues so many audio installations (in particular subwoofers).

 

[Destroysall]

A simple answer is, it depends.
At their base, the 3 are all different connection methods, so it depends on the quality of the receiver circuitry and the implementation.

I have never heard anybody suggest or prove that S/Pdif is superior over USB, as it depends which device in what context.etc. 
Newer DAC's such as the BiFrost, utilize Asynchronous USB transfer, which basically makes it immune to the same types of errors and timing issues that is prevalent S/Pdif connection types.

I have built many digital transfer systems, Coaxial, Optical, USB and have found that one is never always better in comparison to the others, it depends on the implementation of the circuit.
Some have great Coaxial inputs, some have better optical inputs, some have better USB inputs.

I would say read some reviews and talk to the owners of the BiFrost, great thing about it is you don;t have to buy the USB circuit and can add it later if you want to.

As for the Coaxial to optical, again it depends on the receiver circuits.

So in general, is it much more dependent on the receiver (the DAC) than the sender (the PC motherboard, etc)?

 

[ROBSCIX]

Both really...
It is not an easy questions that A is better over B...it depends on what you have to work with.

 

[Destroysall]

Quote:

 
In my opinion PURE i-20 is a perfect signal source for a DAC. If you compare what you get out of it with amplifying analog signal straight from the iPhone, you'll never listen to music direct from the iPhone again. The whole debacle USB vs. Toslink vs. Coax is insignificant, if you put it against digital vs. analog output from the iPhone.
 
Regarding Toslink vs. Coax - in ideal conditions they are the same. But this world being somewhat less than perfect, you may encounter differences. As ROBSCIX said: which one is better - it depends.
 
Both connections start with exactly the same signal, and if all goes well they both end with the same signal too. The question is what happens in between.
 
Coax is just a wire between the sender and receiver. It is simple but vulnerable, especially if the cable is long. Electrical cables tend to work like aerials: they pick up all the electromagnetic signals in the surrounds. The longer the cable, the bigger the chance of catching some radio stations, powerlines hum etc. Combine that with the signal getting weaker when the cable gets longer and your receiver (DAC) has a really tough job interpreting the garble that comes through. So if you go for Coax, my advice is use the shortest cable you can (less than 2m is rarely a problem). 
 
Toslink is a bit more complicated: it uses fibreoptical connection between the two devices, so the electrical signal needs to be first converted to light impuleses at the source, and then decoded back to electrical at the receiver. Technologically not a big deal, but it introduces more components in the chain (i.e. more things to go wrong). The fibreoptics are much better over long distances, are totally immune to all the electromagnetic interferences, but the cable itself is more fragile - in particular it doesn't tolerate sharp bends, kinks etc. The side benefit is also that the two devices are electrically decoupled, so the connection is not going to introduce the dreaded power frequency hum that plagues so many audio installations (in particular subwoofers).

Well, if I go with the PURE i-20 as a signal source, both the dock and the Schiit Bifrost will practically be less than a foot away from each other.  So in that situation, all I would really need is maybe a half-a-meter digital coaxial cable to suffice such a need.  Doing some more research and found out that glass digital coax cables are among the best, so maybe I could grab one of those? 
 
As ROBSCIX said, the Bifrost being upgradeable is perhaps one of its many highlights in my eyes.  If I ever decide to have the Bifrost as a desktop audio setup, I could either just use the Digital Coaxial input or just add-in the USB input.

 

[Acclaim]

   
This is a frequent topic around here, albeit I know first hand that finding anything useful in search results is an art that only a few have mastered, so I'll make it easy for you and provide the only true and valid answer: it depends
 
On the surface one could think that it doesn't matter: it's the same digital information passed between the PC and the DAC, so whichever way it gets there, the DAC has to chew through the same stream of zeros and ones. But it turns out that there is a difference. 
 
The SPDIF is a dedicated, specialised standard for passing digital audio signals between devices, while USB is an universal data transfer interface. So the specialised protocol should be better than the universal one, right? Well - read on...
 
At this point the respected reader of this message probably should reach for a stiff drink, as we're about to get really technical. If the technical staff doesn't scare you, then pour yourself one anyway to level with me, as I'm enjoying one right now
 
Ready? Here we go...
 
For the digital signal to be properly converted to analog, it needs to be fed to the converter (DAC) in precisely timed intervals, which correspond to the sampling rate of the digital audio file. If the timing is off, it will manifest itself on the analog side as jitter, noise and distortions. How to avoid or at least minimize these nasty effects? The answer is... no - this time there is a straight answer: make sure that the clock used for this timing is as precise as possible. But there is one problem with that: precision is expensive...
 
So how does this all affect our little dillema of choosing one digital interface over the other? As it turns out, these two ways of passing the signal differ in one quite significant detail: SPDIF passes the data already timed at the source, while USB leaves that responsibility to the receiver. 
 
Now those who haven't finished the drink yet should still be able to draw their own conclusion, but I'm on the second one already so I can't resist to offer my own: if your signal source has a better clock than the DAC device, then using SPDIF may indeed result in a better quality output. The problem is that more often than not, the devices we use as sources have very cheap (read: inaccurate) clocks. The onboard sound modules that most PC motherboards offer are notoriously bad, similar story with CD players where this type of connectivity is usually considered just a tick on the marketing blurb.
 
On the other hand, if someone builds and sells a dedicated DAC, they do understand that the only justification of its existence is quality. Motherboards already have DACs, so if you're going to buy one it's only because what your PC offers is not good enough. So when direct comparison is not possible, I'd bet that the receiver (DAC) will do a better job timing the data stream than the sender (motherboard of your PC).

This is a fantastic explanation that should be stickied. If not for much more than to give fellow head-fiers an excuse to pour themselves a stiff one!

 

[PleasantSounds]

  This is a fantastic explanation that should be stickied. If not for much more than giving fellow head-fiers an excuse to pour themselves a stiff one!

 
Thanks for the kind words but be careful what you wish for: one expensive hobby is enough 

 

[thecrow]

That was fantastic and shed a lot of light.

I'll assume it's all the truth

Thanks for posting.

 

[abitdeef]

Hi all!

I had a question concerning the two signal transports, Digital Coaxial and USB. I am not sure which part of the forums this thread should truly be categorized under, but I posted here in the "Computer Audio" forum due to my question concerning the Digital Coaxial output on my PC's motherboard. Moderators, please feel free to move this if necessary.

Any who, my question is what are the pros and cons of both outputs? I have always used USB, but I am considering upgrading my DAC with the Schiit Audio Bifrost and have considered using it with my PCs motherboard via Digital Coaxial. Is there any sonic differences in using Coaxial rather than USB? I've done some research on this and some say DIgital Coaxial (S/PDIF, I believe) can be much more superior than USB (correct me if I'm wrong). If this is true, it would be great news as I wouldn't have to spend the extra money to get the Schiit Bifrost with a USB output (unless I upgrade to a Mac).

So any info on this would be much appreciated, thanks in advance!
~Destroysall

Quote:


This is a frequent topic around here, albeit I know first hand that finding anything useful in search results is an art that only a few have mastered, so I'll make it easy for you and provide the only true and valid answer: it depends

On the surface one could think that it doesn't matter: it's the same digital information passed between the PC and the DAC, so whichever way it gets there, the DAC has to chew through the same stream of zeros and ones. But it turns out that there is a difference.

The SPDIF is a dedicated, specialised standard for passing digital audio signals between devices, while USB is an universal data transfer interface. So the specialised protocol should be better than the universal one, right? Well - read on...

At this point the respected reader of this message probably should reach for a stiff drink, as we're about to get really technical. If the technical staff doesn't scare you, then pour yourself one anyway to level with me, as I'm enjoying one right now

Ready? Here we go...

For the digital signal to be properly converted to analog, it needs to be fed to the converter (DAC) in precisely timed intervals, which correspond to the sampling rate of the digital audio file. If the timing is off, it will manifest itself on the analog side as jitter, noise and distortions. How to avoid or at least minimize these nasty effects? The answer is... no - this time there is a straight answer: make sure that the clock used for this timing is as precise as possible. But there is one problem with that: precision is expensive...

So how does this all affect our little dillema of choosing one digital interface over the other? As it turns out, these two ways of passing the signal differ in one quite significant detail: SPDIF passes the data already timed at the source, while USB leaves that responsibility to the receiver.

Now those who haven't finished the drink yet should still be able to draw their own conclusion, but I'm on the second one already so I can't resist to offer my own: if your signal source has a better clock than the DAC device, then using SPDIF may indeed result in a better quality output. The problem is that more often than not, the devices we use as sources have very cheap (read: inaccurate) clocks. The onboard sound modules that most PC motherboards offer are notoriously bad, similar story with CD players where this type of connectivity is usually considered just a tick on the marketing blurb.

On the other hand, if someone builds and sells a dedicated DAC, they do understand that the only justification of its existence is quality. Motherboards already have DACs, so if you're going to buy one it's only because what your PC offers is not good enough. So when direct comparison is not possible, I'd bet that the receiver (DAC) will do a better job timing the data stream than the sender (motherboard of your PC).

You know I'm 5 years behind you and one drink ahead and this makes perfect sense. Now I'm not bummed out by the M2s not having coaxial out. I will be feeding it to chord mojo which I assume has much better timing.

Whatever you're doing when/if you read this take a nice shot of fine single malt. Because you deserve it with such a precise but practical explanation.

 

[theveterans]

You know I'm 5 years behind you and one drink ahead and this makes perfect sense. Now I'm not bummed out by the M2s not having coaxial out. I will be feeding it to chord mojo which I assume has much better timing.

Whatever you're doing when/if you read this take a nice shot of fine single malt. Because you deserve it with such a precise but practical explanation.

Is this accidental necrothreading?

Anyways, Chord DACs sound best with the USB input while other DACs sound better with SPDIF (due to crappy USB implementation)

 

[dhc0329]

I have chord tt connected via schiit wyrd at 32bit 192khz vs digital coex at 24bit 176hz. Coex provides noticeably better sound.
Definitely more crisp and clear. On a.b test 5 people all consistently chose coex connection over usb. I was expecting better result with usb
but wasnt the case and also not sure why coex failed to go beyond 176khz. Serious stutter if go above 176, but this could be my
HT omega fenix card.

 

[goodvibes]

This is a fantastic explanation that should be stickied. If not for much more than to give fellow head-fiers an excuse to pour themselves a stiff one!

And the better the dedicated source gets, the bigger divide vs USB which has that limitation even when the PC is made quiet or when using careful reclocked which isn't the same clock. I'm used to good sources and have never liked the USB interface as well. I resorted to firewire/Dice II circuits and linear power supplies etc which was better than USB but not up to SPdif done well. The firewire setup was similar to the Rednet solution with faster clock access and great jitter control but like I said, I personally still prefer SPdif done right. Doesn't mean you can't get the sound you need from a PC based setup. It's just not for me.