[Traum]

Admittedly, USB is quirky at times, also prone to ground loop/hum issues (unlike optical S/PDIF). Other than that, there shouldn't be any noticeable audio quality differences between the (correctly implemented) DAC inputs.

According to both my ears (I only have the gen 1 USB on my Bifrost regular) and from Jason himself, SPDIF sounds better than USB on the Bifrost -- or at least, this is true with the gen 1 USB interface.

Here is a review article about the Bifrost (regular) from Nov 2012:

http://www.audiostream.com/content/schiit-audio-bifrost-dac

Specifically,

From the Schiit website's Bifrost FAQ page:

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.

This section of the FAQ seems to have been taken out, so perhaps the gen 2 USB does sound a little better than the gen 1. Still, if your source already has SPDIF, why not use it and save the $100 - $150?

 

[Tuco1965]

Gen 2 USB sounds as good as the other inputs.  If you don't need it, don't buy it, but if you do, it's great.

 

[madwolfa]

Maybe because Schiit's Gen 2 card is using more robust (better chip, async, etc) implementation of USB Audio protocol? I heard their Gen 1 USB implementation was an afterthought...
I'm using all inputs (USB/Coax/Toslink) on my V-DACs and I don't hear any difference. Also Stereophile measurements show jitter level is negligible on either inputs.

 

[Traum]

Good to know that the new gen 2 USB Schiit sounds every bit as good as the SPDIF. Thanks!

 

[RickB]

 
Ah, thanks. It was a mystery to me what was inappropriate about expressing a preference for one Schiit product over another in a Schiit Owner's thread. 

And now an admin has restored my deleted post, which he explained was accidentally removed.

 

[hodgjy]

Good to know that the new gen 2 USB Schiit sounds every bit as good as the SPDIF. Thanks!

I just got a new Bifrost the other day, and I'm still working it though the paces.  I got it fully loaded with USB 2nd gen and Uber.
 
To my ears, I can hear no difference in optical and coax.  I haven't tried the usb yet, but I'm expecting to hear no difference.  I can hear differences between amps and DACs, but I can't hear any difference in digital protocol with the Bifrost.  I did, however, hear a difference in USB over coax with the V-DAC ii.  USB was a little more congested.

 

[Traum]

I just got a new Bifrost the other day, and I'm still working it though the paces.  I got it fully loaded with USB 2nd gen and Uber.

To my ears, I can hear no difference in optical and coax.  I haven't tried the usb yet, but I'm expecting to hear no difference.  I can hear differences between amps and DACs, but I can't hear any difference in digital protocol with the Bifrost.  I did, however, hear a difference in USB over coax with the V-DAC ii.  USB was a little more congested.

Hey Hodgiy,

Congrats on the fully loaded Bifrost Uber! If you have a chance to get around trying out all the different inputs, I'd love to hear your impressions on whether you notice any difference between them.

 

[hodgjy]

Hey Hodgiy,

Congrats on the fully loaded Bifrost Uber! If you have a chance to get around trying out all the different inputs, I'd love to hear your impressions on whether you notice any difference between them.

Right now my laptop is at my office, but I might be able to try the USB over the weekend.

 

[paradoxper]

I've had much the same experience. Gungnir's USB and Optical were the same to me, Uber Bifrost much the same, though I didn't keep that in house very long. I've heard some difference with using the PWD and some other's,
but nothing that's ever made me think optical was inferior and it's still my preferred choice.

 

[madwolfa]

 
UPDATE: After some listening I can definitely confirm my impressions... The 'low gain' setting is much gentler to my ears. Sound is comfortable, mid-high frequencies are tamed down and the harshness is gone. It sounds more balanced and natural. Maybe less 'punch', but I definitely prefer it this way.

 
Here's what Jason told about Asgard's 'low gain' mode...
 

Asgard 2 uses #2 and #3--cascode topology, and much higher voltage rails (80V, as opposed to Asgard 1's 32V rails) to reduce distortion. It also uses a small amount of feedback in the low gain mode. So, distortion and output impedance are even lower in the low-gain mode (0.005%-ish and 0.6 ohms--ish). 

 

[huberd]

I am glad someone explained how the low gain mode in the Asgard2 works, I had a hunch that Jason was just adding negative feedback. Adding negative feedback improves the sound. You can clearly hear it in the low gain mode. I asked the guys at Shiit if they could implement negative feedback in the Valhalla too but they said no. I wonder if they could make a Valhalla2 with a low and high gain mode? I did read that a tube naturally has negative feedback built in. Not sure if this is true but then it would not benefit from adding it to the circuit if it is. 

 

[fenderf4i]

i used these instructions, i'm pretty much a novice myself, but if one is careful, methodical, its pretty easy , the lights to go back in the holes gives some folks trouble, i used a pair of extra long needle nose pliers to help insert the LEDs  page 2, post 25 give some pictures
http://www.head-fi.org/t/661444/schiit-bifrost-uber-analog-upgrade

No need to use pliers or anything to line the LED's up. The trick is to slide the circuit board into the main aluminum casing FIRST, which inserts the LED's into the holes very easily, THEN slide the dark grey inner casing in last. It took me all of 10 seconds to get the LED's in correctly this way. I am betting this is how they're originally assembled.

 

[Dook0]

Hi everyone, 
I would like to pull the trigger for the gungnir and mjolnir combo.
The thing is I am moving a lot (every 6 months) mostly in Europe and US.
Is there any custom/mod for switching between 115V and 230V ? That could be awesome !
 
Thank you !

 

[hodgjy]

  Hi everyone, 
I would like to pull the trigger for the gungnir and mjolnir combo.
The thing is I am moving a lot (every 6 months) mostly in Europe and US.
Is there any custom/mod for switching between 115V and 230V ? That could be awesome !
 
Thank you !

That would be cool.  But, I think all you'd need is a step transformer so you can run the non native plug in the other country.  Would work just fine.

 

[kothganesh]

Hi everyone, 
I would like to pull the trigger for the gungnir and mjolnir combo.
The thing is I am moving a lot (every 6 months) mostly in Europe and US.
Is there any custom/mod for switching between 115V and 230V ? That could be awesome !

Thank you !

Hi everyone, 
I would like to pull the trigger for the gungnir and mjolnir combo.
The thing is I am moving a lot (every 6 months) mostly in Europe and US.
Is there any custom/mod for switching between 115V and 230V ? That could be awesome !

Thank you !

I was in the same boat and ended up with the 230v. You just need to keep a transformer with you whenever you are in the "other" voltage zone.
Good luck.