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How to properly send audio from MacBook to external DAC

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#1
I've done plenty of research on this one but seem unable to find a definitive answer...

For music, I simply stream from Idagio (flac) and Google Music (high). I do not use TIDAL, nor do I download and play high res audio files from iTunes or another player.

I have a MacBook Air connected via USB to Topping E30 (then THX 789 to HD6xx). The mac's Audio Midi Setup program offers a variety of outputs to the E30 from 24b/44.1khz to 32b/768khz.

Given the above, what is the best output setting to use for the E30?

Thank you.
 
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#3
I have a MacBook Air connected via USB to Topping E30 (then THX 789 to HD6xx). The mac's Audio Midi Setup program offers a variety of outputs to the E30 from 24b/44.1khz to 32b/768khz.

Given the above, what is the best output setting to use for the E30?
Set it to whatever your music files are. Mostly FLAC? Set it to 44.1kHz and 16 bit.
 

jhm

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#4
I just set mine to the highest supported by my DAC (768kHz in the case of my D90).

All of the programs which I use (e.g. Qobuz, Amazon Music, Chrome, Safari etc) will downgrade it as necessary to fit whatever you are playing the time.
 

Blumlein 88

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#6
My opinion with some facts behind it. You'd like to send the same bit depth and sample rate to the DAC as the original file your playing. No processing, up or down sampling is done to it that way.

So for 16 bit 44khz send that. For 24 bit, 48 khz send that. For 24 bit 192 khz send that. You are sending the most faithful version possible to the DAC.

Now some people have reasons to think upsampling and sending it to a DAC capable of higher sample rates makes the DAC perform better. I doubt it myself though with a poor DAC there could be some truth to it. My answer is don't use a poor DAC.

If you are using the free Idagio, then 16 bit 44 khz should do the trick. With Google music as well.

If your DAC takes 32 bit 768 khz, then something along the way must upsample that. Maybe with some good software that is okay, might notice no difference. I'd just use the native sample rates and bit depths and not worry about it. 44.1 khz and 16 bit should do for your two sources of music.

Now what is the downside if I'm wrong? If some upsampling helps a little, then how much does it help? I'm highly skeptical it is an audible difference (excepting a DAC with really poor output filtering which isn't the case with your DAC). If there is a difference it would be very minor one you'd strain to hear as different. Fidelity to the source is usually a very good idea and a clarifying guide in these situations.
 

jhm

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#7
The behaviour depends on the program you use.

I have a Mac connected to a D90:

* Qobuz on macOS - Qobuz adjusts the connection to the DAC up or down to follow the music you want to play. In other words, the connection (as shown in Audio MIDI Setup) is changed by Qobuz and there is therefore no down/upsampling. So, for example, if I play a 96kHz track on Qobuz, the D90's display shows the DAC switching to 96kHz and if I play a 192kHz track on Qobuz, the D90's display shows the DAC switching to 192kHz.

* IDAGIO (set to FLAC) on macOS - it just uses whatever connection to the DAC has been setup by Audio MIDI Setup and it (or - more likely - macOS) up or downsamples the music accordingly. For example, if I set the DAC in Audio MIDI Setup to 384kHZ and play a track using IDAGIO, the D90's display continues to show 384kHz. (This behaviour is the same with Roon and Amazon Music HD.)
 

hyperplanar

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#8
24-bit/44.1 kHz. Sending 16-bit data over 24-bits does not alter it, and 44.1 kHz since most of your music will be in that sample rate unless you have a bunch of high-res files.
 

Frank Dernie

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#9
I just set mine to the highest supported by my DAC (768kHz in the case of my D90).

All of the programs which I use (e.g. Qobuz, Amazon Music, Chrome, Safari etc) will downgrade it as necessary to fit whatever you are playing the time.
I don't think so.
What you set on Audio Midi setup is what the Mac sends, if you are playing a file of a different type it will be re-sampled before it is sent.
I have audirvana and it resamples to whatever you set or sends the unmodified file the choice is in the preference (as is the resampler code).
I haven't decided if I can hear the re-sampling or not. I have heard degradation by a poor re-sampling algorithm in the past but I think most now are good so likely to be fine.
 
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jhm

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#10
What you set on Audio Midi setup is what the Mac sends, if you are playing a file of a different type it will be re-sampled before it is sent.
Thanks for clarifying! Yes, except for (at least from the programs which I am using) the Qobuz app on macOS which changes the rate in Audio Midi setup depending on the sample rate of what's being played.
 

lashto

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#11
I've done plenty of research on this one but seem unable to find a definitive answer...

For music, I simply stream from Idagio (flac) and Google Music (high). I do not use TIDAL, nor do I download and play high res audio files from iTunes or another player.

I have a MacBook Air connected via USB to Topping E30 (then THX 789 to HD6xx). The mac's Audio Midi Setup program offers a variety of outputs to the E30 from 24b/44.1khz to 32b/768khz.

Given the above, what is the best output setting to use for the E30?

Thank you.
some reading
https://www.thewelltemperedcomputer.com/SW/OSX/OSX.htm. Should clarify why you are not getting a clear/definitive answer: there isn't one.
https://www.thewelltemperedcomputer.com/SW/OSX/iTunes.htm Applies not only to iTunes but to any (simplistic) music app that just uses the default OS audio path.
 

Frank Dernie

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#12
Thanks for clarifying! Yes, except for (at least from the programs which I am using) the Qobuz app on macOS which changes the rate in Audio Midi setup depending on the sample rate of what's being played.
Thanks, I have qobuz and hadn't noticed, mind you I mainly stream 44/16.
I have edited my post to add audirvana which can be sdet to resample too, or not.
 

Vincent Kars

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#13
Multiple streams
All popular operating systems (Windows, OSX, Linux, Android) are designed to play multiple audio streams.
You watch a video but you want to hear a notification when a email arrives.
The only way to obtain this is to mix the audio and the system sound.
You can only mix if all streams run at the same sample rate.
The audiostreams are converted to float (to keep the quantization error down), mixed, dithered and converted back to integer.
Dither (adding random noise) is applied to decorrelated the audio and the quantization error.
In case of 16 bit, it is a must.
Today as most DAC’s do have a 24 bit input, you might wonder is dither at -144 dBFS is of any significance.

An obvious consequence of multiple audio streams is that you do have to choose a fixed sample rate and a bit depth in the audio settings of the OS.

Bit depth.
Simply set it to the max as supported by your audio device.
If you play a 16 bit file and the setting is 24 bit, 8 zero bits are added with zero impact on sound quality.
Choosing the highest bit depth regardless of your source can be beneficial when applying DSP.
Something as simple as digital volume control will result in loss of resolution if the bit depth is 16 bits.

Turn the volume down with 48 dB
1111111111111111
0000000011111111 only 8 bits left using a 16 bit word length.

Do the same using a 24 bit word
111111111111111100000000
000000001111111111111111 still 16 bits left using a 24 bit word length.

Sample rate.
This is a different matter.
Certainly in the past, re-sampling often means disaster. It resulted in measurable and audible distortion.
Today it is done pretty transparent.
Your best bet is to set the sample rate to what is common.
Most of our audio is 44.1 kHz.


768kHz!
This is probably the max the USB UAC2 audio receiver accepts.
As USB does device enumeration, you probably see all supported sample rates in the audio panel.
Don’t be surprised if the DAC (the chip inside the box) runs at a completely different rate. In fact most DAC’s do apply ASRC (Asynchronous Sample Rate Conversion) to get rid of the input jitter hence do have a free running clock.
The consequence of 768 is all the audio is resample twice, up to 768 by the media player and then down to xxx by the DAC.

IMHO
- set bit depth to the max supported by the audio device
- set the fixed sample rate to what is common (44.1 kHz)
- if possible use automatic sample rate switching
 
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#14
There should be no audible difference between the DAC of your MacBook and your USB UAC2. They both measure audibly transparent.
 
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