[Dillan]

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[NA Blur]

Here are a few quotes from their site:
 
"
Well then, how about your USB? Is it fully buzzword compliant? 24/192? Async?
It is absolutely buzzword compliant! Not only is it USB async, but it’s USB 2.0 async that’ll do up to 24 bits/192 kHz sampling rates. Yes. USB 2.0. Not antique 1.1. It works without drivers on Mac and we provide drivers for Windows 8, 7, Vista, and XP. It’s a good-sounding, reliable, solid implementation of USB. But that’s like saying, “Well, its a very nice meal, given that the chef could only work with McDonald’s hamburgers.”*
 
Wait. Are you saying USB is crap?
We’re saying we put a ton of time into our USB implementation, but, to our ears, USB still doesn’t quite offer the performance of SPDIF. And we can even get into shades of gray on SPDIF too: consider Mike Moffat’s AT&T ST-optical interfaces and Sumo’s Axiom/Theorem transport and D/A, which had a separate low-jitter master clock connection from the transport."
 
http://schiit.com/schiit-faq/about-bifrost/
 
I find the USB 2.0 to my Grace m903 quite music and they pretty much guarantee extremely low jitter which is a huge source of noise for DAC.  You should try both with cheap cables and see which you like better, but the USB implementation will be just fine I am sure.  They should have provided drivers if you are using a Windows based PC.  They say that it should be driverless for MAC.

 

[PurpleAngel]

Quote:

My motherboard has optical (and of course USB). Right now i have my Bifrost plugged in via USB to my motherboard, then plugged into my Asgard with RCA cables. Now, most people will say that USB is a bad way to go, my only other option is optical.. I'm just not sure how it works exactly and am wondering, before I go that route, if it actually makes a difference. Should i buy a decent optical cable? If i were to do that, how would my computer know to use the Bifrost as my sound card, without the data coming through from my USB? Would the USB just be completely replaced by the optical cable? Thanks in advance for helping me understand.

Using USB bypasses the motherboard's built in audio features.
S/PDIF (optical & coaxial) allows you to use the on-board's audio features.
 
optical cables
http://www.monoprice.com/products/subdepartment.asp?c_id=102&cp_id=10229
 
Make sure you have updated to the latest drivers for your built in audio.
Try using Foobar2000 for music audio.

 

[Dillan]

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[Dillan]

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[PurpleAngel]

Quote:

Thanks for the reply, thats what i was afraid of. I don't really want to use the on-board sound in anyway, I'd much prefer to only use the Asgard and Bifrost.. while completely bypassing my motherboards on-board sound. I guess its usb only for me then.

Just because you connect with optical, nothing if forcing you to use the on-board audio features.
I would say to get the optical cable and at least try connecting optically, just to compare to USB.
You can also order "premium" RCA cables for connecting the Bifrost to the Asgard.
Or any other cables from Monoprice, they have low prices and low cost shipping.

 

[NA Blur]

Here is what Wes Phillips noticed going from USB to OPTICAL on the Grace Design m902:
 
Yikes! But John, I'm not convinced I love the DAC, despite John Marks' rave last June.
 
"Ditch the USB connection," he said tersely. A TosLink connector was at hand—and went in.
Much better. The murk disappeared, and the bass was quite a bit more solid and seriouser—a good thing when you're listening to funk. It sounded good enough, in fact, that I began listening to uncompressed and lossless files stored on my hard drive. Now that was definitely more like it.
 
http://www.stereophile.com/content/grace-design-m902-reference-da-headphone-amplifier-wes-phillips-grace-m902
 
Personally I was never able to test the optical side of the DAC on my m903, but would love to hear from anyone else who has done it.  I could not get my PC to send the signal via optical on the back of my soundcard / video card.

 

[HamilcarBarca]

Quote:

Here is what Wes Phillips noticed going from USB to OPTICAL on the Grace Design m902:
 
Yikes! But John, I'm not convinced I love the DAC, despite John Marks' rave last June.
 
"Ditch the USB connection," he said tersely. A TosLink connector was at hand—and went in.
Much better. The murk disappeared, and the bass was quite a bit more solid and seriouser—a good thing when you're listening to funk. It sounded good enough, in fact, that I began listening to uncompressed and lossless files stored on my hard drive. Now that was definitely more like it.
 
http://www.stereophile.com/[...]

 
If Stereophile's claims are true (which is certainly not a given), they've demonstrated a defect in the M902's USB interface.
 
However, it's much more likely that Stereophile's claims are overblown nonsense (which is often the case), This is, after all, the same magazine which compares HDMI cables and finds both audio and visual differences (where the differences they report are either imaginary or tailored to suit the advertisers.)

 

[NA Blur]

Quote:

 
If Stereophile's claims are true (which is certainly not a given), they've demonstrated a defect in the M902's USB interface.
 
However, it's much more likely that Stereophile's claims are overblown nonsense (which is often the case), This is, after all, the same magazine which compares HDMI cables and finds both audio and visual differences (where the differences they report are either imaginary or tailored to suit the advertisers.)

I agree with your thoughts on this, but since I am unable to test it I figured I would at least list one persons take on it.
 
Do you have any experience comparing USB to optical?  Could you comment on that if you do?

 

[Dillan]

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[Currawong]

Back when there was much discussion about it, the only USB receiver chip available was the PCM2706/2707, which is pretty poor. Toslink is a very poor digital connection. On a scope you can't even get a proper square wave.  The newer USB chipsets, on the other hand (such as the Bifrost uses) are far better. Depending on the way things are set up in the DAC (and assuming it doesn't require power from the computer) about the only improvement possible would be to cut or isolate the 5V power supply to reduce the amount of noise the DAC receives from the computer.
 
Though it doesn't include USB and is referring to CD transports, a long but interesting read about digital transmission can be found here:
 
http://lampizator.eu/LAMPIZATOR/TRANSPORT/CD_transport_DIY.html

 

[tomb]

I know you mean well, Currawong, but I strongly disagree that the PCM2706/2707 is a poor USB receiver chip.  That's a sweeping generalization that dismisses many of the top DACs on the market.  One might say the fascination with 24bit is a flash-in-the-pan compared to the tried-and-true.  I'm not saying either is correct, just that implementation is everything ... and probably always will be.

 

[One and a half]

I compared optical on m903 with the USB and it's no contest. Optical sounds thin and bland, USB can go to 192/24, there are ways of minimising noise between USB and DAC.

 

[Currawong]

Quote:

I know you mean well, Currawong, but I strongly disagree that the PCM2706/2707 is a poor USB receiver chip.  That's a sweeping generalization that dismisses many of the top DACs on the market.  One might say the fascination with 24bit is a flash-in-the-pan compared to the tried-and-true.  I'm not saying either is correct, just that implementation is everything ... and probably always will be.

 
Fair call, but some of my opinion is the result of discussion with manufacturers about its performance and not just about high-res. I wont get into the whole async etc. discussion as I know I'd be talking out my rear in that case. 

 

[ROBSCIX]

Try both but I would still say given the receiver on the BiFrost, USB is probably the best way to go.  Even for S/Pdif, not all I/O is created equal and an onboard would probably give you very poor signal quality in comparison to the USB.