Quick Question: Usb DAC or optical DAC

[upstateguy]

Hi Guys

I did a quick search and didn't see any comments about a usb dac vs. an optical dac.

Which is the best way to go?

Thanks

USG

[fjf]

I have one with both and I use optical, because I've read that the optical glass cable isolates the DAC from electrical noise created by the computer. However, otherwise both should sound good.

[labrat]

I have an Overture from HeadRoom, which has both, and I believe I can hear a slight difference when switching between USB and optical from the same computer to the Overture DAC.
With the optical as a winner.
But just very slightly!
The USB is not a protocol made for audio especially, the S/PDIF is.
And not all computers have optical-out.
So I believe you should make you own decission on this.
Many very cheap USB-DAC's ( small USB-devices powered by USB) available, optical DAC's need power-supply and are not available as cheap devices!
Good luck searching!

[Elephas]

I use the CEC DA53 which is an external standalone DAC with optical inputs as well as USB. The USB input sounds very good playing ALAC on iTunes and is comparable to optical inputs from the E-MU 1212m or AirPort Express.

[Don Quichotte]

It's not addressing your question so neatly, but I have compared:
1. the hard drive (EAC ripped tracks) -> foobar -> kernel streaming -> USB out -> 19 feet USB cable (actually two cables connected) -> Apogee mini-Dac with Asio driver installed, to
2. my Cambridge Audio D300 CD player -> coaxial out, BNC terminated -> very short DIY digital cable using Belden 1505A cable and very cheap connectors -> Apogee Mini-Dac
The Apogee is a reclocking Dac, but generally speaking the transport, digital cable etc. still make a noticeable difference.
Conclusions:
a) when the CD in the CD player was a CDR, option 1. was better (USB)
b) when the CD in the CD player was an original CD, option 2. was better (coaxial out), but the difference was smaller than in case a)

Too many variables, but I think at their best the two options are close, with the USB more convenient and the SPDIF potentially a little bit better sounding. Still, take into account that my experience is very limited.

[Jon L]

The problem with current crop of DAC's with "USB input" is that USB is not implemented correctly. They just use off-the-shelf USB chip, most using the least-desirable isosynchronous USB transfer method, negating the great potential benefits of USB transfer.

Also, most of these USB DAC's internally convert USB data into spdif anyway before D to A conversion stage.

Ideally, USB data transfer should be done asynchronously, then data should be passed on to DAC chip via native I2S bus internally. I do not know of any "USB DAC" that does this.

For lesser of two evils, a heavily-engineered, "optimized" USB to spdif converter can sound very nice, though. But this is way beyond the cheap implementation of most USB DAC's...

[eduj]

I m on the same boat.I recently got a FSC Amilo laptop and it has SPDIF output,firewire and USB ofcourse.I want to get an external sound device:either DAC or USB/Firewire card.But i want to be able to EQ the sound.Can i do that with the optical>>>DAC or i can only EQ the sound with a USB soundcard?(The HD is full of FLAC and i use Foobar2000)

[ScubaSteve87]

I was going to go USB or firewire for a while, but then I found tha they make a right angle toslink mini adapter. Now I can use the front optical out on my laptop!!! But in any case, I migh switch to airport express anyways. I had never really looked at airport express before, but now that I see it... I realize... ITS AWESOME

[keiron99]

Originally Posted by Don Quichotte

a) when the CD in the CD player was a CDR, option 1. was better (USB)
b) when the CD in the CD player was an original CD, option 2. was better (coaxial out), but the difference was smaller than in case a)

Are you saying you can hear a difference between an original CD and a CDR of the original? That beggars belief to me - you really must have golden ears! As long as the ripping software has read the original correctly and the copy been burned correctly (and you can verify this if you use EAC), you have two identical discs. How could there possibly be any difference?

[Don Quichotte]

Originally Posted by keiron99

Are you saying you can hear a difference between an original CD and a CDR of the original? That beggars belief to me - you really must have golden ears! As long as the ripping software has read the original correctly and the copy been burned correctly (and you can verify this if you use EAC), you have two identical discs. How could there possibly be any difference?

I'm afraid it's not a matter of having golden ears, the difference is quite audible (even on low quality CD players if the headphones or speakers are very good). The copy is bit perfect, true, but has more jitter than the original. Every CD writer, even every kind of CDR organic substance (at least between cyanine and phtalocyanine, on my CD player) has a different sound signature because of the different amount, type, pattern or whatever of JITTER. Check out the Bob Katz' articles on www.digitaldomain.com (I think) for a more in-depth explanation.

[keiron99]

Originally Posted by Don Quichotte

I'm afraid it's not a matter of having golden ears, the difference is quite audible (even on low quality CD players if the headphones or speakers are very good). The copy is bit perfect, true, but has more jitter than the original. Every CD writer, even every kind of CDR organic substance (at least between cyanine and phtalocyanine, on my CD player) has a different sound signature because of the different amount, type, pattern or whatever of JITTER. Check out the Bob Katz' articles on www.digitaldomain.com (I think) for a more in-depth explanation.

Well, it's certainly not audible to me (ripped to PC or directly through CD transport, to Pepetual Tech p3A DAC, to Stax Lambda Sig Pros). I can't pretend to understand jitter - but from my limited knowledge I don't see why a CDR should introduce more of it than an original. In any case, some components, such as the Perpetual Technologies P1A virtually eliminate jitter from the chain. Furthermore, there is also debate about whether jitter really does effect the audible quality of the signal at all.

It would appear that is not the correct link.

I would be keen to know whether other people here can detect a difference between a CD original and CDR, preferably under blind conditions.

[dsavitsk]

Originally Posted by Jon L

Ideally, USB data transfer should be done asynchronously, then data should be passed on to DAC chip via native I2S bus internally. I do not know of any "USB DAC" that does this.

http://www.ecp.cc/NOS-USB-DAC.html

Parts arrived today. Boards should be here on monday.

[Ferbose]

For me the answer is simple: optical.

Digital output via TOSLINK has been a standard for a long time, and it is likely to stick around for at least 20 years. Consumers think optical is cool, and professionals like its immunity to ground issues and EMI. There is no reason to discard TOSLINK, especially in consumer audio.

USB on the other hand, keeps evolving and requires software/driver support. 10 years down the road, can a USB DAC still work with the new computers? Who knows what computers will even be like in 10 years? Will there still be USB in 10 years?

If I want to use a DAC for 10 years or more, I would choose optical or coaxial S/PDIF.

[Solude]

USB no matter the implementation is an electrical medium. The PC regardless of cost is a switching machine that pollutes the electronics. That pollution looks like jitter to a DAC. Its not data jitter, that will always be near perfect, but the electrical jitter that rides the signal is huge to the tune of ~500ps.

For this reason alone, optical is always preferred if both options are available.

[randyruiz]

Originally Posted by Don Quichotte

I'm afraid it's not a matter of having golden ears, the difference is quite audible (even on low quality CD players if the headphones or speakers are very good). The copy is bit perfect, true, but has more jitter than the original. Every CD writer, even every kind of CDR organic substance (at least between cyanine and phtalocyanine, on my CD player) has a different sound signature because of the different amount, type, pattern or whatever of JITTER. Check out the Bob Katz' articles on www.digitaldomain.com (I think) for a more in-depth explanation.

Not only that but the quality of the plastic used in the jewel case also alters the sound signature. You see the jewel cases covered in a 1nm layer of chrominium alters the quantum frequency of the phtalocyanine or cyanine in the CD and dramatically alters the soundstage and mid range. Everyone should use chrominium covered jewel cases.