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Optical TOSLINK vs. USB: Which connection is better to connect a DAC?

post #1 of 105
Thread Starter 

My options are, from my computer:

 

X-Fi Fatalty Optical Out > DAC

 

OR

 

USB > DAC

 

I would get the Transparent Performance USB Audio Cable if I go USB, or something from Audioquest if I run from my sound card's optical out.

 

DAC I plan on using is the Music Fidelity V-DAC.

 

Which will be better?

post #2 of 105
Thread Starter 

Anyone?  I KNOW there has to be some heavy opinions on this topic..

post #3 of 105

You might try a repost (and search) in the computer audio thread.  I've tried both, I don't find much difference, if any.  I use optical from my airport express (arguably mid-fi) to my Nova and Headroom Ultra.  I use USB and Optical sort of interchangeably from my macbook pro to the Headroom ultra.  I can't discern a difference.

post #4 of 105

I am not an expert at this but from what I heard, they each have their own strengths and weaknesses.

but the prominent thing is the implementation of the USB or optical input in the DAC. 

one DAC may work better with USB than optical or visa versa. 

I hope that helps :)

post #5 of 105

One advantage of optical is that it electrically decouples your DAC from your source.  Sometimes this can be a huge advantage, such as cases where your DAC is being powered by the USB port of a computer and is getting switching noise.

 

Also, USB is only stable to about 20 feet (if you're lucky), whereas optical should be stable to at least 330 feet (100 meters).  (It will actually work even farther in most cases, but I believe the spec is 100 meters.)   That's another big advantage.

 

So for those reasons, I always choose optical over USB if it's an option.

post #6 of 105

Toslink is direct digital signal from your soundcard, that's should be better.

 

USB's signal should be: Soundcard-> PC's mainboard-> USB chip-> USB cable ->DAC's USB receiver.

 

I've tried coxial vs. USB with my PC, coxial is more better. (I've mod. my card, removed Toslink to BNC connector)

post #7 of 105

I've tried both and unfortunately, I didn't like either - compared to a Halide Bridge USB to SPDIF converter. I was only using a cheap USB printer cable. For toslink, I used a glass toslink cable. BTW, I'm not sure how much difference a high end toslink cable will make - there's quite a bit jitter via toslink, from what I understand. I would like to try an audiophile USB cable like the one you mentioned.

post #8 of 105
The V-DAC uses an asynchronous sample rate converter (hence the claim for ultra low jitter). The sonic differences in between digital inputs should be zero.

The arguments for optical over USB would be isolation of the computer ground (can induce some noise in some designs) and the fact that your soundcard optical output is probably not as dependant as USB from the CPU. USB can be laggy when there is an heavy load on the CPU (not so much of a problem with modern CPU). The drivers for your soundcard might also be better optimized for gaming than the generic USB audio drivers.
Edited by 00940 - 12/23/10 at 2:28am
post #9 of 105

I prefer the sound of USB, (denser, warmer and more present) but if you have a noisy computer system, (interference) optical will isolate that noise and may in some cases give you better sound.

post #10 of 105

I have a digital and usb out, and the digital out sounds better.  I also bought a Monarchy DIP that goes between my DAC and input source.  So with the DIP in there, the difference between my computer and i170 is slight.

 

Also to consider when looking at optical is the physical makup of the cable.  Is the media plastic or glass?  From my experience if you are using glass in your fiber cable the difference between coax and optical is very little.


Edited by mikemalter - 12/25/10 at 10:11am
post #11 of 105
Quote:
Originally Posted by danielghofrani View Post

I am not an expert at this but from what I heard, they each have their own strengths and weaknesses.

but the prominent thing is the implementation of the USB or optical input in the DAC. 

one DAC may work better with USB than optical or visa versa. 

I hope that helps :)



This.

 

If asynchronous and galvanically isolated, go USB.

 

If asynchronous and handles high bit word length go USB

 

If USB has line noise in it, go optical.

 

If usb has no line noise but is isochronous go optical.

 

Dave

post #12 of 105
Quote:
Originally Posted by myinitialsaredac View Post





This.

 

If asynchronous and galvanically isolated, go USB.

 

If asynchronous and handles high bit word length go USB

 

If USB has line noise in it, go optical.

 

If usb has no line noise but is isochronous go optical.

 

Dave



 


Too much of a generalization imo... Implementation is at least as important as the technology by itself. Bad grounding/decoupling practices or HF noise riding on the PS lines for example can degrade the best theoretical design.

The funny thing with the V-DAC (which uses the SRC4392, based on the SRC4192) is that you can't indeed measure any jitter in USB mode (with a PCM2706 in adaptive mode), while the SPDIF inputs (hence the optical one) aren't that perfect. See : http://www.stereophile.com/content/musical-fidelity-v-dac-da-processor-measurements Looks like there might be problems with the implementation of the SPDIF receiver of the SRC4392...

Isochronous USB can btw be just as perfect as asynchronous. If you combine a decent isochronous USB receiver (such as PCM2706-7) with the SRC4192, the ASRC will function pretty much like a buffer and there is 0 jitter due to USB making it to the DAC (read here: http://www.diyaudio.com/forums/digital-source/46413-any-feedback-new-cs8421-high-res-asrc.html ).

 

post #13 of 105
Quote:
Originally Posted by 00940 View Post





 

Too much of a generalization imo... Implementation is at least as important as the technology by itself. Bad grounding/decoupling practices or HF noise riding on the PS lines for example can degrade the best theoretical design.The funny thing with the V-DAC (which uses the SRC4392, based on the SRC4192) is that you can't indeed measure any jitter in USB mode (with a PCM2706 in adaptive mode), while the SPDIF inputs (hence the optical one) aren't that perfect. See : http://www.stereophile.com/content/musical-fidelity-v-dac-da-processor-measurements Looks like there might be problems with the implementation of the SPDIF receiver of the SRC4392...Isochronous USB can btw be just as perfect as asynchronous. If you combine a decent isochronous USB receiver (such as PCM2706-7) with the SRC4192, the ASRC will function pretty much like a buffer and there is 0 jitter due to USB making it to the DAC (read here: http://www.diyaudio.com/forums/digital-source/46413-any-feedback-new-cs8421-high-res-asrc.html ).

 



You are correct, I did generalize too much.

 

Though I would say that my generalizations are correct most of the time. 

 

Are there any DACs that currently use those chip lineups?

I was under the impression there were no dacs that use a buffer currently.

The issue I would argue still lies in using the computer clock. In that thread they specify that the chip if the jitter input is low will correct for theoretically all of it, however if it is high it will still cause phase modulation. 

 

I think the theoretical ideal would to be using error-correction transfer into a buffer and clock it out on the DAC side.

Matter of time eh?

 

Dave

post #14 of 105

I'm currently using a udac with Alessandro MS1i's and AD700's. I thought about upgrading to the Maverick D1, would it be worth it to keep my udac as a usb to coaxial converter, or just connect the D1 via usb?

 

I'm using a laptop and don't have any digital audio outputs.

post #15 of 105
Quote:

I think the theoretical ideal would to be using error-correction transfer into a buffer and clock it out on the DAC side.

Matter of time eh?

 

I believe the Chord QBD76 already does this. Doesn't matter though, I still get a different sound from USB, toslink, and Halide Bridge. The best sound sound is via Halide Bridge, but I'm sure if I spent beaucoup bucks on a USB cable, or connected the toslink to a nice sound card instead of my Macbook's digital output, I'd get much better results that might comparable to the Halide.

 

What I'm trying to say is even with the most sophisticated jitter rejection technology DACs, the sound is still sensitive to high jitter.

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