Plexamp headless distorsion - passthrough possible?

Plex Labs
1

I have an issue where I get audible distorsion from my newly installed Plexamp headless RPI (great feature). I have gone through a lot of different settings without success. Lowering volume seems to improve bit I would like to have fixed volume on as high lever as possible.

Is it possible to get audio passthrough on the headless version? The settings on playback seems to have little impact on the sound output level.
(for me).

2

are you using the built-in analog/headphone output from the pi?

below is cut and paste from some install/setup notes I wrote for myself (some of it might be relevant to your question, you can ignore the rest) …

  • note that Plexamp headless currently does NOT touch the system (ALSA) volume/gain settings for your selected audio device … if you initially experience audio that is either distorted or too quiet, you should check your device gain settings using the OS alsamixer utility, preferably before changing any playback settings in the Plexamp app itself. For example, the built-in headphone output on the Pi allows for up to +4dB above unity gain, which can lead to distorted output (recommend setting alsamixer gain to 0dB or slightly below in this case). Audio devices with a built-in amplifier and volume control, such as USB headphone DAC/amp dongles, can default to a reduced volume setting that’s safe for headphone use. If you’re connecting a device like this to an external amplifier/receiver with its own volume control, you might want to increase the alsamixer gain to its max (unity gain) level.
3

Thanks for the feedback! I’m using an external DAC (Focusrite 2in2) but what you write explains why the settings didn’t seem to make any difference. I’ll check alsamixer and see if that does the trick.

4

Gain was set to 0 db PCM output. I’m using a loopback before the actual DAC. I can reduce it a couple of dBs and do a long term test to see if it help out. For feelgood it would have been nice to know where the volume is increased.

5

Plexamp is bit-perfect on Linux as long as:

  • EQ is disabled.
  • Loudness leveling is disabled.

We’ve heard some reports of distorted audio on Linux which are more mysterious and related to the ALSA mixer/output chain and/or devices downstream.

6

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