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Strange problem with USB DAC

post #1 of 14
Thread Starter 

I recently purchased a new Windows 8.1 desktop PC and combined it with a Schiit Modi USB DAC.  I frequently experience clicks in the audio playback, but with rather peculiar behavior. I'm fairly certain that the "clicks" I hear are due to insufficient data being sent to the USB DAC, so that it has to fill in the gaps in the playback with a click or gap of some sort.  I've been testing various changes for the past two days.


My computer was restarted after each change to guarantee the changes took effect.


These modifications have no effect:

-Changing USB port

-Changing USB port power settings

-Disabling all other devices on the same IRQ channel such that the USB DAC is alone on both its USB hub and IRQ

-Disabling antivirus and all other such processes/services

-Disabling all superfluous graphical effects

-Disconnecting all other external devices and replacing HDMI monitor with VGA

-Adjusting advanced system performance options to optimize performance of background services rather than programs


This modification affects audio playback, but has no effect on the "clicking" problem:

-Changing bit and sampling rate settings in the Windows advanced playback properties and/or in the media player options


This, bizarrely, appears to fix the clicking problem and allows my audio to play flawlessly:

-Keep a web browser window open


I'm not joking.  If my media player is the only program open, then I hear a click about once per second.  If I keep a Chrome window open along with my media player, then I can listen to music for hours and not hear a single click.  I don't understand it, but I guess I've solved my problem.  Considering how shaky this "fix" seems, though, I wouldn't be surprised if it stops working tomorrow.


I am using iTunes version (that's a lot of ones) for playback.  iTunes playback preferences are set to "Windows Audio Session", 44.1 kHz, 24-bit.  Windows playback properties are also set to 44.1 kHz, 24-bit.  All equalizer/effects are disabled in both iTunes and Windows.  My USB 2.0 cable should be fine and is 6 ft long.  Changing from "Windows Audio Session" to "Direct Sound" fixes the clicking problem, but produces crappier sound quality overall.

post #2 of 14
Thread Starter 

The behavior is proving to be repeatable.  Through multiple reboots and closing and reopening of Chrome and iTunes, the behavior is consistently the same:

When Chrome is open, the audio played by iTunes does not suffer from "clicking" problems.  When Chrome is not open, the audio played by iTunes through the USB DAC "clicks" consistently.


What's more, this behavior appears to be specific to the Chrome web browser.  I've tried opening other programs and web browsers instead of Chrome and nothing else has had the same effect.  Very strange.  My first guess was that maybe Chrome was forcing my PC into Direct Sound mode or something, but I don't think that is the case because aside for the clicks disappearing the instant I open Chrome, I notice no change in audio quality.

post #3 of 14
In the sound configuration through the control panel, try using the following settings:

Make sure iTunes is set to use WASAPI output (I'm not an iTunes user, so can't tell you how to do it). This will then bypass all the Windows sound processing.

Note that with these settings, when playing back music with my media player, I have to close out my media player before I can play sound in my browser because the media player has taken exclusive control.
post #4 of 14
Thread Starter 

Thank you for the reply, cel.


Yes, I have already set these parameters in both the Windows advanced playback properties and in iTunes playback preferences.  And you are correct that you must restart iTunes before any such playback changes take effect (to be safe, I have also tried rebooting the whole PC).  iTunes can play audio with either "Windows Audio Session" or "Direct Sound".  I've been trying to use "Windows Audio Session" because it seems to give me better audio quality when it's functioning properly, but it also leads to more of the clicks.  iTunes may just suck at interacting with WASAPI.


I really don't want to switch media players because all of my 10,000+ tracks are sorted and rated in iTunes, and I use it for smooth syncing to my iPod.  Also, as far as I understand it, iTunes should be capable of bit-perfect playback in WASAPI mode.

post #5 of 14
Sorry. I don't know how to help you, then. I used to have some noise with my internal sound card, but no longer with my ODAC.

I would suggest calling Schiit to see if they can help. That doesn't mean that they can solve your problem, but they might have a good idea of what's causing since they do design their own USB DACs.
post #6 of 14

What happens if you already have Chrome running before you start iTunes?


Does it click then? Or is it the effect of starting Chrome that appears to 'solve' the problem?

post #7 of 14
Thread Starter 

If I have Chrome running before starting iTunes, then it does not click.  So it is not the act of opening Chrome, but rather just having Chrome open.


Also, I just updated my iTunes to version, but that didn't change anything.

post #8 of 14

wondering if this is related to win8 not other software, have known people to have issues with older drivers when trying to use USB audio interfaces...  I am not a PC genius so beyond me in all honesty

post #9 of 14
Thread Starter 

Thanks for the feedback from everyone that has been chiming in.  I've sent an email to Schiit to see what they say.


I'm guessing it's some strange iTunes/Windows 8 issue though, and it may just keep working with this iTunes+Chrome combo.  It's actually giving me great audio quality in this setup -- far better than when I was just using the PC soundcard.

post #10 of 14

I don't know **** about iTunes. Or Schitt for that matter. Realistically - only guessing.




Is it possible for you to set your parameters to 44.1 & 16?


All your iTunes must be 16 bit. Trying to push out the resolution to 24 bit wouldn't make the slightest difference. If it's not there to begin with it's not possible to add it later.



post #11 of 14
Thread Starter 

I've tried all variety of the different bit and sampling rates, and changing that seems to have no effect on the clicking issue.  Whether I run at the lowest option (16 bit, 44.1 kHz) or the highest option (24 bit, 96 kHz), it clicks about the same amount and opening/closing Chrome has the same effect.


(And, yes, when I change the bit and sampling rates I make sure to change it in both the Windows settings and in the iTunes settings and to close and reopen iTunes to make sure the change takes effect.)


As for whether there's any point in me running 24 bit: you're probably right in that 24 bits is giving me no benefit over just running 16 bit.  The math confuses me a little on that, though.  A lossless 16-bit, 44.1 kHz CD rip claims over 900 kbps.  16 bits/sample * 44100 samples/sec = 705600 bits/sec.  Where are those extra 200 kbps coming from?  That's something I can look up elsewhere... but those >900 kbps values were what initially motivated me to use 24 bits before I thought to check into it better.

post #12 of 14
Thread Starter 

Schiit responded quickly, but didn't have too much to add.  We're basically chocking it up as "one of those" things with Windows.  That's just sorta the life of a Windows user: some things are conditionally operational, and you never really know when a future update to the OS, drivers, or program software is going to fix or break something for you.


Schiit did make an interesting comment that I wasn't aware of: apparently Windows does not support the USB Audio 2.0 Standard exactly, but both Linux and Mac do.  So issues with Windows, while still rare, are more common than issues on Linux or Mac.

post #13 of 14

That's an interesting comment. Any chance you can post up the actual text of the claim from Schitt? I've never heard that before.




post #14 of 14
Thread Starter 

Their first reply, after I stated my situation and trouble-shooting attempts, was just that it sounded like a system-related issue.  When I tried to probe a bit more and asked if anyone else had experienced similar issues with Windows 8 and/or iTunes, here is the email reply from Schiit:


"None that we’ve heard of that replicate your exact problem. Windows in general has some problems in 0.5-1% of cases, since there are so many system configurations, software, bloatware, etc. If they just supported the USB Audio 2.0 Standard like Linux and Mac, everything would be easy. No problems with those OSes."

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