Route Audio Output Through USB Audio Jack

Question

I've an rPi Zero that I want to connect to my speakers to utilise it as an AirPlay receiver via Shairport.

I've made the same setup with my Model B+ and it works great. However, even though I made the same setup for my Zero, I can't seem to get the audio routed correctly since my B+ routes it via HDMI(the default) and I need the Zero to output it as analog.

Hardware Setup:

rPi Zero has a dedicated power connection. The data connection is connected to a USB Hub. And the hub connects the Wi-Fi adapter along with the USB to audio/microphone jacks converter.

Software Setup: I've [Shairport-sync][1] installed and configured. My iPhone recognises it and can send the music. However nothing comes out of my speakers.

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I know that I need to use amixer to route my audio, however, the command amixer cset numid=3 1 yielded no success.

Here is the output of some related commands:

lsusb:

Bus 001 Device 004: ID 0bda:8179 Realtek Semiconductor Corp. RTL8188EUS 802.11n Wireless Network Adapter
Bus 001 Device 003: ID 0d8c:0014 C-Media Electronics, Inc. 
Bus 001 Device 002: ID 1a40:0101 Terminus Technology Inc. Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

amixer controls:

numid=3,iface=MIXER,name='PCM Playback Route'
numid=2,iface=MIXER,name='PCM Playback Switch'
numid=1,iface=MIXER,name='PCM Playback Volume'
numid=5,iface=PCM,name='IEC958 Playback Con Mask'
numid=4,iface=PCM,name='IEC958 Playback Default'

What should I do to correctly route my audio?

Answer 1

Finally figured out what to do.

The problem was some ALSA config files have been moved around and the tutorials I've looked up until the question were out-of-date.

This post's accepted answer, helped me solve it.