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Sound path possibilities with DAC+ DSP via USB

Keith Gardner

December 01, 2021 23:50

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I am trying to set up an external DAC with EQ or DSP (in a single unit) to go between my computer (as the source) and the powered speakers (or other audio output system). I want connection from source to be hardwired, to avoid inherent Bluetooth / AirPlay delays.

Simplest form, picture an external USB DAC, with some tone controls, output via RCAs to the audio output. 

Not finding that, exactly, I found the DAC+ DSP. It does what I want, plus a hell of a lot more sound shaping through the DSP, which is fine. Not as quick and easy as I was looking for, but far more sophisticated, so I can work with this. 

I think my only question is, can I route the digital audio out from my Mac, say, via USB, and send that signal as input to the Raspberry's USB, and from there go through the DAC and DSP and ultimately to the speakers? I think the real question is can that RPi USB-A port receive digital audio data from my source system? 

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3 comments

• 0
  
  HiFiBerry team December 02, 2021 05:58

  You can't connect you Mac to one of the USB ports of the Pi to transmit audio. However, many Macs have an SPDIF output (together with the headphone). You should check this about your model. If it doesn't have one, an USB->SPDUF interface is probable easiest way.
  TOSLInk can be connected to the TOSLInk input of the DAC+DSP.

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  Keith Gardner December 02, 2021 16:47

  To put it into today's vernacular, I was (literally) today years old, when I discovered that my Macs support S/PDIF via the headphone port. Who knew? I had utterly no idea. Never done anything with TOSLink or S/PDIF. I think you have solved my problem, which is outstandingly cool.

  Actually it looks like I can even do it standalone, without the Raspberry Pi, right?

  I've got a bit of learnin' to do now. Thanks so much. 

  Edited by Keith Gardner December 02, 2021 16:59
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  Henk Bezuidenhout February 27, 2022 11:49

  Sorry to dig up a post from the grave, but this advice is incorrect as of February 2022.
  
  The Raspberry Pi Zero 2 W and the Raspberry Pi 4 both support USB gadget mode fully for Class 2.0 audio source/sink for sample rates all the way up to 96khz 32-bit. I have successfully set up a Raspberry Pi 4 to act as a USB audio device by plugging the USB-C to a host computer (Note: power is restricted and might cause issues with the SD card for long term use, the Pi Zero 2 W has no such limitation as the USB gadget port is a separate port to the power port). There are some bugs with Windows when dynamically changing the sample rate form the Pi, but it works flawlessly on my MacBook Pro. 
  
  Do note, that this is quite a complex task, it takes a while to get working and you need to be familiar and comfortable with the Linux command line, compiling the Linux kernel and with general troubleshooting. You can find a guide for the Pi Zero 2 W here: https://www.hackster.io/masonrf/rpi-zero-2-w-audio-gadget-448a6a 
  
  The only steps you need to change for the Pi 4 is when compiling a new kernel, you need to follow the instructions linked in the tutorial.