[funnyletter]

I've been using a USB DAC (nuForce Icon uDAC-2) with my OSX machines for ~18 months, and with my retina Macbook Pro running OSX 10.8 since August. In the last few weeks it's started to have problems. The audio will drop out about 40 seconds into use, and it doesn't come back until I disconnect and reconnect the DAC from the USB port.
 
I initially assumed this was the uDAC crapping out, since it's not the best in the world, and bought a fiio e17 to replace it. However, the fiio e17 is having the exact same problem.
 
I've now reproduced the problem with two different DACs using multiple USB cables, multiple hubs, and connected directly to my laptop via each of its two USB ports. The problem persists, leading me to believe it's not a problem with the cables, the DACs, or my USB hubs.
 
Googling produces references to some kind of USB audio problem in Mountain Lion, but no solutions to the problem. The general solutions to dropout on a USB DAC seem to be "turn off wireless" and "disconnect all other USB devices", but those aren't really viable options for me -- wireless is this laptop's only connection to the internet, and my other USB devices are my keyboard, mouse, and external HD. They're not really optional.
 
Is anyone familiar with this issue? Are there any solutions I should try?
 
Thanks!

 

[netdog]

I haven't had this problem and am running Mountain Lion on my Mini server with USB DAC attached, but I am wondering if you have checked the Apple support forums.  They usually house a treasure trove of information.  http://support.apple.com

 

[funnyletter]

I did some searching in the Apple support forums and didn't find much. The one person I found having a similar problem (albeit with a different version of OSX) doesn't seem to have found a solution.

 

[headpio]

Similar problem here! After upgrading from OSX 10.5 to OS 10.8 on my macbook pro, I started to have issues with audio playback over USB to the Nuforce HDP. The sounds gets distorted for a number of seconds once every 20-30 seconds.
 
Problem occurs:
- regardless of audio app (itunes / cog)
- regardless of audio file (tried various flac / alac)
- only on the external usb dac (Nuforce HDP in my case)
- only since I upgraded to OSX 10.8.3 (I upgraded straight from 10.5.8)
- only when there is other USB activity such as using an USB mouse, or the internal keyboard / trackpad
 
I don't see many hits on google for this issue. If this is a specific incomptibility issue between the Nuforce product line and OSX 10.8, then please let's find out. More feedback needed, please contribute.
 
S.

 

[Currawong]

I suggest this: Open up the Console (.app) which can be found in the Utilities folder inside the Applications folder. When the audio drops out, see what messages appear. With any luck you'll get an error regarding USB that is meaningful.

 

[headpio]

Thanks. There are quite some 'Unexpected connection closure' errors at the time when it happened, but I am not sure they correlate.
 
On day one (after the upgrade to 10.8.3) the problem was quite persistent (e.g. after unplugging the USB device a couple of times). However, on day two and now on day three I haven't heard a single glitch. So far so good, the problem appears to have gone!
 
S.

 

[headpio]

Things were running smoothly, but just now I was having distortion again on the USB audio.
 
OSX Mountain Lion (10.8)
 
Running: Xcode (4.6.1), Firefox, Thunderbird, Terminal, then launched Cog and the audio was distorted as soon as I was using the keyboard.
 
Rebooted ...
 
Running: nothing, launched Cog, audio was fine, then started Firefox, Thunderbird, Terminal, Xcode. Audio is still fine (so far so good).
 
I have contacted NuForce (who were very responsive, thumbs up!) and they state that the NuForce HDP is a basic / generic USB audio device, so if there is an issue it must be related to OSX. I am still wondering if other people are having similar issues with USB audio distortion on OSX Mountain Lion?
 
S.