Independent audio outputs

I was wondering if the 1/4" outputs and the RCA outputs are necessarily the same, or if they’re just mirrored in software. I’m trying to find out if I can use the Zyn (kitv2 with HiFiBerry Pro) both as a synth and then independently as an FX send/receive on my mixer.

Is that possible, or is it something that fundamentally the audio interface can’t do?

Edit: Reading the HFB specs, it’s obvious now that there’s only one DAC, for one stereo pair out. I guess my question becomes what would best practices be for looping the zyn into the fx chain? An idea:

  • All non-zyn sources sent to a submix on the physical mixer
  • send that sub to the zyn inputs
  • Gain 2x2 layer for capture
  • all the zyn synths on other layers
  • the final fx chain getting all the zyn layers, including capture
  • zyn outs to return on physical mixer

I think that’s the closest I can get to using a single zyn for both synth and fx duty. Did I miss anything that would make this use case better, short of getting a USB audio interface for a secondary output?

Hi @sehrgut

Each audio input and output of a Zynthian may be used as a mono audio or part of a stereo pair. By default routing is made as stereo pairs with both inputs being routed to effects chains and both outputs being routed to main output.

Accessing the layer context menu by bold pressing on a layer will allow the input (capture) and output to be routed manually. You can select zero or more inputs and outputs. Most inputs and outputs are available in this routing table which allows you to create the audio paths you want.

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The alternative is an additional sound card via alsa_out: “Using multiple Sound Cards with alsa_in

I use it to route live instruments audio in via usb to the zynthian, apply audio-fx and then back out via USB to distribute to external samplers, while keeping the native HiFiBerry Pro audio in-/out for synth layers and final mix of the output of the external samplers.

I am not sure about latency, but it works well for my purpose.


If you want more that two inputs or more than two outputs you are better off getting a multiple I/o sound card.


Is that better than using the HFB for one pair of outputs and another for a second pair? Is there a major CPU usage or other sort of reason to not run the HFB alongside a USB sound card?

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I give a description of why there is CPU increase using multiple audio interfaces here. Zynthian has to samplerate convert to avoid timing glitches. I am using a Behringer UMC 1820 which gives me 8 mic / line inputs and 8 outputs and it works great. In fact, I no longer use my mixer and just use the Zynthian. (See this thread.)


Thank you! I’ll certainly have to think about my strategy on this. I appreciate the links to the other threads!