How to troubleshoot lack of passthrough on NUC?

alexbelgium · November 5, 2021 at 8:16 PM

Hello,

I would appreciate any help to troubleshoot why passthrough won't work for me.

My hardware :

- NUC6CAYH with libreelec 10.0.1 running from an usb key

- Amplifier : SMSL AD18 connected with usb to the NUC

- Music stored in flac on an usb drive accessible via SMB

My settings :

- Blank installation (so no custom settings except for audio)

- Audio :

- Audio output device : ALSA : SMSL AD18 AMP, SPDIF.

- passthrough : enabled.

- Passthrough device : ALSA : SMSL AD18 AMP, SPDIF.

- all options below checked : AC3, AC3 Transcoding, DTS

My observation:

If I start a music, I see no indication passthrough works : the sound level can be controlled with kodi volume, changing the (non passthrough) resample quality option creates an audible difference, and changing the passthrough device doesn't do anything. Conclusion : passthrough doesn't work.

But why? And what can I do to troubleshoot?

Thanks very much!

**lrusak** · November 6, 2021 at 2:54 AM

It sounds like you aren't actually playing anything that requires using passthrough (AC3, DTS, etc).

alexbelgium · November 6, 2021 at 6:14 AM

Quote from lrusak

It sounds like you aren't actually playing anything that requires using passthrough (AC3, DTS, etc).

Ahah, I was probably overthinking it then.

I thought FLAC could go directly to the amplifier without decoding but as you say it probably just isn't possible...

Thanks for your reply, you saved me a lot of time

**chewitt** · November 6, 2021 at 7:04 AM

FLAC is a lossless format, and sometimes used for multi-channel audio, but not a pass-through format.