[satfrat]

.

[satfrat]

.

[whubbard]

Robin,
I think we might be actually saying very similar things, but were off a bit in our explanations.
I am merely saying that one digital signal out of a computer will be the same as another. Nothing more, nothing less.

SPDIF & USB are really the same thing. It's all 1 & 0,s but they are being transfered in a different encoding. Frankly, as long as all the 1 & 0s are there at the end, no differences will be noticed.

Now, a case could be made that the chip that sends out the 1 & 0s for USB and SPDIF is distorting them, but I highly doubt that is the case. As long as nothing is being compressed, and the DAC chip gets the correct digital signal, technically, there should be no difference. Digital signals don't behave in the same way as analog ones. Thats not to say that data cannot be lost/altered along the way, it's just...different.

Now if the signal is being converted internally to analog, then I completely agree with you. You want that to happen away from the PC as there is much more probability for interference with an internal sound card. Basically it doesn't matter what digital out you choose, it's really the DAC & resulting analog that matters.

From my personal testing, I have tried USB, SPDIF & Fiber. They all sound the exact same to me. I've even run them through good digital converters, and they still sound the same. Essentially you could use any of these inputs, but you really want a good DAC chip. That is whats important.

In regards to you comment about the USB vs. M-Audio, I would just say that the digital signal must have been altered along the way in one of these. Someone was being naughty! Usually this shouldn't happen, and the digital signal should remain intact along the whole line to the DAC, but maybe in your case it did. Our ears can also trick us sometimes, mine sure have.   Also, you mentioned bypassing the sound card. The SPDIF out on most computers is technically 'part' of the sound card, however it is sending out the exact same bits in a different encoding than the USB.

We can get MUCH more technical on this, but for the purposes of a $200 DAC you will not notice the differences!

-West

EDIT: So there were a few posts while I was typing this. I would be shocked if you noticed the difference between SPDIF & USB. They are really essentially the same!!! Some say USB has ground loops and EMI coupling, some say SPDIF is prone to variations because of the world-clock. What is of the utmost importance is the DAC chip and it's implementation. In that regard I think the Zero DAC performs well. Others that come straight from USB (Zero goes USB to TosLink) but have different DAC chips & circuits could sound much worse or much better. All I'm saying is that from personally experience the Zero DAC is the best DAC I've heard under $200.

[satfrat]

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[whubbard]

Does anyone know Steve or Lee's forum name, so I could drop them a message to have them post on this thread? 

If we bring in the experts, we can confirm who's right  .  Of course, I know this isn't a competition.  All the suggestions are really appreciated and it just goes to show I have a lot more to learn before I can make an informed decision.

Steve - audioengr
Lee - cryoparts

I hate to say it, but neither of them are really 'experts' in the field. (No offense Steve or Lee). They both probably know a lot more than I do, but the true experts are those that worked on the SPDIF & USB Codecs and design the chips. Steve and Lee can probably share the insights of what they have heard.

To be fair, Steve is really better suited for this. I'm pretty sure that Lee doesn't really design any of this, he just sells it.

If we want true expert advice, call up Intel.

-West

[satfrat]

.

[cryoparts]

Does anyone know Steve or Lee's forum name, so I could drop them a message to have them post on this thread? 

If we bring in the experts, we can confirm who's right  .  Of course, I know this isn't a competition.  All the suggestions are really appreciated and it just goes to show I have a lot more to learn before I can make an informed decision.

Steve - audioengr
Lee - cryoparts

I hate to say it, but neither of them are really 'experts' in the field. (No offense Steve or Lee). They both probably know a lot more than I do, but the true experts are those that worked on the SPDIF & USB Codecs and design the chips. Steve and Lee can probably share the insights of what they have heard.

To be fair, Steve is really better suited for this. I'm pretty sure that Lee doesn't really design any of this, he just sells it.

If we want true expert advice, call up Intel.

-West

Steve knows what he is talking about.

Lee

[whubbard]

Steve Nugent, who is an Electrical Engineer with 25 years digital design experience in the computer industry designs all of our products. He has a broad experience in digital system and interface design, board layout, transmission-lines and other relevant technologies. Steve was a design-team lead on the Pentium II at Intel Corp. and holds 22 patents in various cable and digital technologies. Steve has had audio as a personal hobby for over 39 years.

Well I stand corrected. I knew Steve was good with Audio products, but I never knew all this about him.
I would really love to hear his thoughts on this debate!

-West

[whubbard]

Well,
Here is a place to discuss you thoughts on this debate.
Do you find that one is plain better?
Do they should the same to you?
Does it vary by DAC & System for you?

Steve, I know we would all love to here your thoughts on this as you were at Intel and from what we can gather, are the most knowledgeable.

-West

[cryoparts]

Hard to answer, depends on how skilled the engineer/designer is and what tools are in his toolbox.  I voted USB, provided someone like Josh from Sonicweld, Steve from Empirical or Gordon from Wavelength designed the USB receiving circuitry.

Lee

[tvyankee]

hey guy's

thought you might want to check this out.

http://www.wolfsonmicro.com/uploads/documents/en/SPDIF_Paper_v1.2%20May%202007.pdf

[audioengr]

Robin,
I think we might be actually saying very similar things, but were off a bit in our explanations.
I am merely saying that one digital signal out of a computer will be the same as another. Nothing more, nothing less.

SPDIF & USB are really the same thing. It's all 1 & 0,s but they are being transfered in a different encoding. Frankly, as long as all the 1 & 0s are there at the end, no differences will be noticed.

Now, a case could be made that the chip that sends out the 1 & 0s for USB and SPDIF is distorting them, but I highly doubt that is the case. As long as nothing is being compressed, and the DAC chip gets the correct digital signal, technically, there should be no difference. Digital signals don't behave in the same way as analog ones. Thats not to say that data cannot be lost/altered along the way, it's just...different.

Now if the signal is being converted internally to analog, then I completely agree with you. You want that to happen away from the PC as there is much more probability for interference with an internal sound card. Basically it doesn't matter what digital out you choose, it's really the DAC & resulting analog that matters.

From my personal testing, I have tried USB, SPDIF & Fiber. They all sound the exact same to me. I've even run them through good digital converters, and they still sound the same. Essentially you could use any of these inputs, but you really want a good DAC chip. That is whats important.

In regards to you comment about the USB vs. M-Audio, I would just say that the digital signal must have been altered along the way in one of these. Someone was being naughty! Usually this shouldn't happen, and the digital signal should remain intact along the whole line to the DAC, but maybe in your case it did. Our ears can also trick us sometimes, mine sure have.   Also, you mentioned bypassing the sound card. The SPDIF out on most computers is technically 'part' of the sound card, however it is sending out the exact same bits in a different encoding than the USB.

We can get MUCH more technical on this, but for the purposes of a $200 DAC you will not notice the differences!

-West

EDIT: So there were a few posts while I was typing this. I would be shocked if you noticed the difference between SPDIF & USB. They are really essentially the same!!! Some say USB has ground loops and EMI coupling, some say SPDIF is prone to variations because of the world-clock. What is of the utmost importance is the DAC chip and it's implementation. In that regard I think the Zero DAC performs well. Others that come straight from USB (Zero goes USB to TosLink) but have different DAC chips & circuits could sound much worse or much better. All I'm saying is that from personally experience the Zero DAC is the best DAC I've heard under $200.

West - A lot of us hear differences.  I just did a demo for the BAAS in Santa Clara last weekend.  We listened to a track (Livingston Taylor) from a really good modified CD transport with good power and digital cables.  Then same track was played from computer HD over USB using Foobar 0.8.3.  Then the same track was upsampled to 24/96 using SRC.  All using the same DAC, amps and speakers.

All listeners heard a large improvement from the transport to the low-jitter USB.  Everyone heard the improvement to 24/96 as well and like this one the best.  I took a poll.

What is the mechanism at work? Primarily jitter improvement and secondarily hi-res.

Steve N.
Empirical Audio

[whubbard]

West - A lot of us hear differences.  I just did a demo for the BAAS in Santa Clara last weekend.  We listened to a track (Livingston Taylor) from a really good modified CD transport with good power and digital cables.  Then same track was played from computer HD over USB using Foobar 0.8.3.  Then the same track was upsampled to 24/96 using SRC.  All using the same DAC, amps and speakers.

All listeners heard a large improvement from the transport to the low-jitter USB.  Everyone heard the improvement to 24/96 as well and like this one the best.  I took a poll.

What is the mechanism at work? Jitter.

Steve N.
Empirical Audio

Steve,
I get that it's possible for people to hear differences, but in theory, if both are bit perfect, it would be the same, no?
So it's really a function of design. Maybe it is easier to design a good USB port than SPDIF?

Also, you must admit that your testing is a very weak argument for USB over SPDIF.   
Frankly, you could say that it was the Computer that was better than the CD player, and the cables made no difference!
Did you compare the SPDIF of the computer to the SPDIF of the DAC? I'd bet they sounded different too...

I remember reading a post recently here where someone else liked SPDIF more than USB. I really think that it might be a matter of preference, but again, I would rather pick a DAC on it's chip and inards than whether it can due SPDIF or USB. Wouldn't you prefer to have a great SPDIF DAC than a good USB DAC?

-West

[audioengr]

Steve,
I get that it's possible for people to hear differences, but in theory, if both are bit perfect, it would be the same, no?

It's a bit of comparing apples to oranges.  USB starts out on most computers with higher jitter, so more is required to squelch it.  S/PDIF can be fairly low jitter to begin with.  If I designed the computer USB interface, I coudl make it really low jitter, better than S/PDIF, so the there is really no answer to this question other than depends on the design of the source computer and the converter device.

So it's really a function of design. Maybe it is easier to design a good USB port than SPDIF?

About the same I think.  They both use off-the-shelf parts, so its implementation, board design, buffering, power delivery etc..

Also, you must admit that your testing is a very weak argument for USB over SPDIF.
Frankly, you could say that it was the Computer that was better than the CD player, and the cables made no difference!

I guess that's true.  What I was really trying to demonstrate is that jitter is audible, particularly from ANY CD transport, and that devices downstream can reduce it audibly.

Another experiment could have been a desktop with a PCI card with S/PDIF output compared to my USB converter implementation.  It would have been the same result though, I have done it, even with a Lynx AES16 or other "pro" audio card.

Did you compare the SPDIF of the computer to the SPDIF of the DAC? I'd bet they sounded different too...

Not sure what you mean here.  PCI add-in cards have S/PDIF output.  The S/PDIF on the DAC is an input.

I remember reading a post recently here where someone else liked SPDIF more than USB. I really think that it might be a matter of preference, but again,

Sure, there are a lot of these.  They are not my products.  They are mostly based on the PCM270X chip from TI, which has given USB a bad name.  Very difficult to minimize jitter with this chip.

I would rather pick a DAC on it's chip and inards than whether it can due SPDIF or USB. Wouldn't you prefer to have a great SPDIF DAC than a good USB DAC?

My order of prioirity is:

#1 Jitter
#2 DAC with simple paths and minimal digital filtering

The chip used in the DAC is of secondary interest, unless of course its an irritating sounding chip (there are a few).  It's more important to look at the design, implementation and the designers skillset.

Just because a DAC has USB does not make it a lesser DAC.  My own Overdrive is one of the best and it just happens to have USB as well as S/PDIF and I2S inputs.  I'll welcome shootouts with the best non-usb DACs on the planet.  Just had one last weekend at the Bay Area Audiophile Society with their best-voted DAC.  It was not USB.  We used a Fireface 400 to drive it S/PDIF.

Steve N.

[Crimson]

Hi Ray,
In my 'Budget' PC system I use the Zero DAC. You have to get it off Ebay, but it's worth it, and you'll find some pretty rave reviews around. I use the SPDIF out. It comes with a USB converter, but I am under the belief it is better to use the SPDIF out. If you use the USB output your just sending it through more components to achieve supposedly the same results. If the USB does a good job converting, then you have the same things as just using the SPDIF, therefore, just use the SPDIF. I really hope that makes sense...

-West

I dunno about that West, by using the SPDIF, it's my understanding that when using the computer's sound card, the card itself is being subjected to all the internal interference when coverting the signal inside the computer whereas by using the USB, you bypass all that interference by having the signal converted outside the box. It's one of the main reasons why I spent the $$$ on a quality USB cable USB transport instead of simply using my M-Audio sound card w/ SPDIF out as had when starting out with computer audio.

The cheapest way tho is to simply use the sound card and digital cable.

Cheers,
Robin

Curious if you've started ripping to lossless yet, and what your thoughts are.

[boead]

SPDIF & USB are really the same thing. It's all 1 & 0,s but they are being transfered in a different encoding. Frankly, as long as all the 1 & 0s are there at the end, no differences will be noticed.

That's not true. They are very different animals.


BTW: I’ve had a number of DAC’s that were SPDIF (optical toslink and coaxial) and USB. The SPDIF cables all made huge differences in sound, yeah even the opticals (glass being by far the best) where as I’ve found very little differences between USB cables.

..and how your computer interfaces (delivers the music) via USB and SPDIF has a giant impact on the end result.

I lover Scott Nixons I2C USB DAC by the way.

[cryoparts]

...so its implementation, board design, buffering, power delivery etc..

The nail has been hit on the head!

Lee

[chrisby]

Steve, Lee, et al:

Forgive the newbie computer audio question, but as a recent convert to iMac & soon iBook, are there any recommendations for "affordable" Firewire vs USB DACs?  So far I'm quite happy enough with iTunes user interface - it has all the functionality I need, and it's certainly handy to have a large library available at the click of a mouse. 

My equipment layout is such that the desk-top iMac is at the "wrong" end of the listening room - at least 30ft of interconnect would be required to get to the DAC/pre.  As my current DAC (Citypulse) only has coaxial and optical inputs, I'd need to upgrade to use either USB or FW.  I've been given to understand that USB2 would likely have significant quality issues at that distance.  If so does this also apply to Firewire or optical?

I briefly tried the Airport/AEX, which is fine for convenience, but .... well 'nuff said 'bout that - it should come as no surprise that even with cheap stock internconnects, direct coax or optical was significantly superior.

[cryoparts]

I'll leave specific recommendations to others who aren't in the biz.  There are a lot of good inexpensive DAC's on the market right now.  Plus, my idea of "affordable" tends to not be same as others, I've been told...

30ft is too long for USB.  You could get an Opticis system if you wanted to do USB.  Coaxial (provided it is a good cable) would be fine.  I wouldn't do optical that long, personally.

Peace,

Lee

[rydenfan]

Steve, Lee, et al:

Forgive the newbie computer audio question, but as a recent convert to iMac & soon iBook, are there any recommendations for "affordable" Firewire vs USB DACs?  So far I'm quite happy enough with iTunes user interface - it has all the functionality I need, and it's certainly handy to have a large library available at the click of a mouse. 

My equipment layout is such that the desk-top iMac is at the "wrong" end of the listening room - at least 30ft of interconnect would be required to get to the DAC/pre.  As my current DAC (Citypulse) only has coaxial and optical inputs, I'd need to upgrade to use either USB or FW.  I've been given to understand that USB2 would likely have significant quality issues at that distance.  If so does this also apply to Firewire or optical?

I briefly tried the Airport/AEX, which is fine for convenience, but .... well 'nuff said 'bout that - it should come as no surprise that even with cheap stock internconnects, direct coax or optical was significantly superior.

It all depends on your definition of "affordable"