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Problem solved! Getting 24/96 signal out via USB on MacBook Pro

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Posted on January 28, 2015 at 22:55:20
junkscience
Audiophile

Posts: 18
Location: West
Joined: January 11, 2005







Having just tracked this issue down, I thought I would post it here:

The solution to the problem in connecting an external DAC to a MacBook Pro (Mac OS X) to pass the high resolution (hi rez) file at 24/96 audio out via the USB cable to the DAC:

"The trick is to set 24/96 for output, but 16/96 for input. It seems that OS X reserves the bandwidth on the UBS chain for input, even though the DAC will never use it"
http://www.head-fi.org/t/590961/96-khz-24bit-integer-output-via-usb-to-burson-ha-160d-on-latest-os-x-not-working-solved

Step 1: Audio MIDI Setup > Window > Show Audio Window
Step 2: Select the ***Connected*** USB DAC in left hand column (e.g, Maverick Audio ...)
Step 3: Select "Input" and set "Format" to "2 channel 16 bit integer" -- (this is the obscure non-intuitive step)
Step 4: Select "Output" and set "Format" to **** 2 channel 24 bit integer" **** -- (this is the goal)

 

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RE: Problem solved! Getting 24/96 signal out via USB on MacBook Pro, posted on January 29, 2015 at 05:05:37
junkscience
Audiophile

Posts: 18
Location: West
Joined: January 11, 2005
 Currawong on a follow up post at Head-Fi notes that "Another one I found: Make sure the bit depth is set to 24 bit before trying to set the sample rate. OSX wont allow high sample rates at 16 bit."

 

RE: Problem solved! Getting 24/96 signal out via USB on MacBook Pro, posted on January 29, 2015 at 05:14:45
lokie
Audiophile

Posts: 1988
Location: Georgia, USA
Joined: January 28, 2003
You have to do this set up before you want to play 24/96 files. If you leave it at that setting, how does it play 16/96 files?

 

RE: Problem solved! Getting 24/96 signal out via USB on MacBook Pro, posted on January 29, 2015 at 06:43:10
junkscience
Audiophile

Posts: 18
Location: West
Joined: January 11, 2005
 Another found pearl, but somewhat obvious again once you know:
In the Audio Midi Setup dialogue box (Output), "there are two volume-control sliders, for the left and right channels. These should be set to maximum, to prevent OS X from scaling the signal before sending it out – if you want to do volume control in the computer, let the music player itself do it."

 

RE: Problem solved! Getting 24/96 signal out via USB on MacBook Pro, posted on January 29, 2015 at 09:49:30
AbeCollins
Audiophile

Posts: 46280
Location: USA
Joined: June 22, 2001
Contributor
  Since: February 2, 2002
 I'm glad you solved the problem for your Mac and DAC but I don't think your solution is applicable across the board.

It seems odd to me that your DAC shows 2in/2out. Is it an analog to digital converter and digital to analog converter combo? Why would you set the Line In? My DACs do not show up as having Line In settings.

When I select my DACs as the output device, the volume slider is inactive and I have no choice for selecting anything on the DACs input... just the output sample rate as shown below. This is with my PS Audio or my Oppo DAC.

iTunes does not have the ability to change sample rate to match the sample rate of the file you are playing. If you select 96000.0 Hz as your output sample rate in Audio MIDI setup, all of your files will be sampled to that rate including your lower resolution 44.1 KHz CD rips and higher resolution 192KHz files. Many other players that can be used standalone or in conjunction with iTunes will perform automatic sample rate switching for you, (and bypass Apple's Core Audio for improved sonics.)

Note that my DAC shows 0in/2out (no inputs / 2ch output). If I choose an output format of 96000.0, that's what it starts at but my player (Audirvana+) will automatically change it to match the file that I am playing. If I view Audio MIDI setup after playing a 44KHz file that pull-down selection will have automatically changed to 44100.0 Hz.

Also note that I play my music through the DAC but any inadvertent computer generated alerts and sound effects and such are played through the speakers in my attached monitor via HDMI. These 'computer sounds' are not routed through the DAC (as denoted by the square happy face icon to the right of HDMI device). You can just as easily set these computer generated sounds to go to your built-in output device which would be your computer's internal speakers. This way only music will ever come through the DAC and the rest of the audio system.

My present DAC setup


My Mac summary



 

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