Shairport-sync: Shairport on RPi3: no sound from airplay

[perizoqui]

Hello,
I'm sure I'm missing something obvious, so thanks in advance for your patience and help!

I've got the latest DietPi, Roon Bridge, and Shairport installed on my RPi 3. Works perfectly as a Roon endpoint. No issues. Bit perfect, high-data rate, perfect.

Airplay, however is not working. The RPi shows up as an Airplay device, and I can select if from my Mac, or Apple TV as an audio output, and it even says the music is playing, but no sound comes out my speakers... The volume is fine on the preamp, it's fine in ALSA.

When I run:

shairport-sync -v

I get the following at the bottom of the file:
Successful Startup
Unable to listen on IPv4 port 5000. The error is: "Address already in use".
Unable to listen on IPv6 port 5000. The error is: "Address already in use".
Could not establish a service on port 5000 -- program terminating. Is another instance of Shairport Sync running on this device?
Request to shut down all rtsp conversation threads

When I run:
ps aux | grep shair
I get the following:
shairpo+ 985 0.0 0.3 26108 3644 ? Ssl Aug10 0:00 /usr/local/bin/shairport-sync
root 3572 0.0 0.1 4276 1876 pts/0 S+ 03:06 0:00 grep shair

Thanks in advance!

[perizoqui]

Solved! It was all a formatting error for what my USB DAC expected to see (24 bit 3 little endian over the 16 bit default).

$ cd /usr/local/etc/
$ nano shairport-sync.conf

Change the following section
alsa =
{
mixer_control_name = "PCM";
};
to:
alsa =
{
mixer_control_name = "PCM";
output_format = "S24_3LE";
};

Works great!