[DaveBlake]

I probably should know this, but asking publically in case the answers (I hope I get) help others.

I am using a USB DAC (Arcam irDAC) with Kodi 17.1 on a RPi 3. Under Settings>System>Audio for the audio output device I am offered 2 options:

- ALSA: ARCAM USB AUDIO, S/PDIF
- ALSA: ARCAM USB AUDIO, Analog

I always use the Analog one (with Number of audio channels set to 2), and it sounds just great. But with the S/PDIF one selected, instead of number of channels I get to set a "limit sample rate" value.

What are the technical differences between these in processing by Kodi, and what is passed to the DAC?
Which option (Analog or S/PDIF) should I choose to get the best audio result?

[popcornmix]

The S/PDIF option has the capability of DTS/AC3 passthrough, but it can also handle stereo PCM.
If you are not using passthrough I'd expect the behaviour to be identical.

[ve3bwp]

I'm just getting started with Kodi on a Rpi3 to replace a WDTV Live box.

I tried getting the onboard Rpi sound card to output SPDIF with no luck. Tried feeding it into the coax output of my receiver with no luck. Analog and HDMI audio works fine.

Is it possible to get DTS/AC3 output from the onboard card or do I need to order a USB sound device that is SPDIF coax or TOSlink out?

[popcornmix]

Is it possible to get DTS/AC3 output from the onboard card or do I need to order a USB sound device that is SPDIF coax or TOSlink out?

You'll need an external device for SPDIF output.
Either a HDMI audio splitter, an SPI audio HAT, or a USB audio card.

The first two options are more likely to work without trouble.
USB audio cards can be tougher to get working (especially with passthrough formats) so I wouldn't buy one of those without seeing someone reporting it works well.