Hi, I am using my d4 mamba and schiit asgard as a DAC + AMP setup. The USB is connected to the d4, and the 2RCA to 3.5mm connects the asgard to the D4's line out. No matter where I connect the USB to, I can hear computer noise. How do I fix this? New DAC? :S

Define "computer noise" and how is the Mamba drawing power?

Does this noise fluctuate with the volume control on the computer, Mamba, or Asgard? Does it fluctuate based on computer activity? Or is it a constant hum? Does it matter what headphones are connected (and does this change the volume of the noise? if yes, list what cans)? If you remove the Mamba from the equation and plug the Asgard into the PC's analog outputs, does this change anything? How about plugging the headphones into the Mamba (with the Asgard disconnected)?

It's a high frequency noise, that changes intensity / volume. By USB.
 
It fluctuates only when the Asgard changes volume. Not on computer activity. I didnt compare with headphones. Removing the mamba makes it slightly worse. Plugging it just into the mamba makes it slightly better and I can only hear noise during songs and for 5-10 seconds after no song is playing. 
 
Thanks for your help btw.

How high freq?

So to clarify:
The Mamba completely unplugged and not involved with the system (unplugged from everything and power), and the Asgard plugged straight into the PC's analog out, is worse?

And if the Asgard is removed from the equation (unplugged from power and connections) and you connect to the Mamba it improves the scenario?

Quite high
 
Yes.
 
Yes. It's quieter and only happens when a song is playing or a couple of seconds after. 

My hypothesis is that the USB connection is just not good and introduces a lot of noise, and the asgard is a better amp than the d4's so it exposes this. You tell me

When I turn up the volume on my amp which is hooked up to the laptop via the headphone out, I start hearing very fast clicking noises which sound very much like an old desktop hard drive; which leads me to believe much of the noise in my laptop circuitry is provided by the constant whirring and clicking of the mechanics inside it - perhaps a solid state hard drive would decrease the noise slightly? - this is only a theory wrapped in an idea, but it doesn't sound too far fetched for my imagination 

jmarsiglio said:

Quite high

Yes.

Yes. It's quieter and only happens when a song is playing or a couple of seconds after. 

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Interesting. I think the "only happens when a song is playing or after" is because in that scenario the Mamba is still "locked" and isn't muted (lots of DtoAs will auto-mute to hide their noise floor with nothing playing, and because it's generally a good practice).

jmarsiglio said:

My hypothesis is that the USB connection is just not good and introduces a lot of noise, and the asgard is a better amp than the d4's so it exposes this. You tell me

Click to expand...

I'm skeptical. If the noise is also coming through on the analog feed from the computer, that sort of rules the USB ports out - it logically follows.

Is this a desktop or a laptop computer?

greq said:

When I turn up the volume on my amp which is hooked up to the laptop via the headphone out, I start hearing very fast clicking noises which sound very much like an old desktop hard drive; which leads me to believe much of the noise in my laptop circuitry is provided by the constant whirring and clicking of the mechanics inside it - perhaps a solid state hard drive would decrease the noise slightly? - this is only a theory wrapped in an idea, but it doesn't sound too far fetched for my imagination 

Click to expand...

Doubtful. It's likely a grounding issue that is endemic to cheaply made computer hardware (and sorry to say, but most all laptops ever made will fit into this). The disk is simply drawing power when it's seeking, and likely exposing the issue further.

A separate controller should eliminate the issue, however if that controller draws power from the system and that power is garbage, it may have issues itself (which is what I'm thinking is happening above). With a proper quality mainboard, separate audio controller, and good PSU, you can use any disk you want with no issues (unless the disk itself is audibly noisy (I've got some old SCSI disks that are real burners and you can hear them spin up from across the room)).

If it actually is noise from the computer, I had the same problem a few years back with my first dedicated USB DAC. Solved mine by getting a cheap 7 port powered USB hub that I still use to this day.

It's a desktop computer. What is a separate controller?
 
Okay well I will try and get a USB hub, if that doesn't work I guess I'll just have to live with it. It doesn't bother me too much because I can't hear it when music is playing...
 
Thanks for all your help guys!

jmarsiglio said:

It's a desktop computer. What is a separate controller?

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Separate controller = not integrated audio. Since it's a desktop, how much do you know about it? (If it was a laptop, I was going to tell you to unplug it from the wall and see if the noise stops - this is a common issue).

Okay well I will try and get a USB hub, if that doesn't work I guess I'll just have to live with it. It doesn't bother me too much because I can't hear it when music is playing...

Thanks for all your help guys!

Click to expand...

The hub might be a good idea too, since that'd be a separate power source. But it's entirely possible to replace the power supply inside the PC too.

I built it, so I know what's in it It's an Antec EA-650W green before you ask! http://www.newegg.ca/Product/Product.aspx?Item=N82E16817371044
 
Btw, when you asked to plug it in without using d4 mamba as a DAC, I plugged it into the soundcard (Xonar DG) which I bought just for surround simulation in games...

jmarsiglio said:

I built it, so I know what's in it  

Click to expand...

Do share.

PSU: Antec EA-650W green
mobo: Gigabyte ud3h-z77x
ram: 8gb gskill
cpu: Intel i5 3570k
SSD: Crucial m4
HD: Hitachi 2TB 
Soundcard: Asus Xonar DG
 
I don't know if I forgot anything, I got some fans in there...

Would your recommendation be to buy a USB hub? If so, where?
 
Oh, GFX card: Gigabyte GTX 670

jmarsiglio said:

PSU: EA-650W green
mobo: ud3h-z77x
ram: 8gb gskill
cpu: i5 3570k
SSD: crucial m4
HD: Hitachi 2TB 
Soundcard: Asus Xonar DG

Click to expand...

How about some manufacturer names. Anyways, my *best memory guess* is that's an entry level Antec PSU. So ripple should not be off the charts. Gigabyte boards should also be stable enough. Which makes this an equally annoying issue.

When you're connecting to the PC, are you using the Xonar or the board's audio out? Have you tried plugging your headphones straight into the PC? (And what headphones are you using; how sensitive are they?).