Exactly my microphone is set as default device, but with a few small changes to a config file (asoundrc) we can control whatever setting we need.
IIRC I've already mentioned this..?
For example, I need SPDIF on my main pc as SPDIF via optical cable is in use yet alsa starts with the microphone as the default audio out (go figure..). Out of 3 possible audio devices alsa chooses the microphone over HDMI and SPDIF out.. Also both SPDIF channels are muted on boot and the backup of asound.state seems to be ignored. But there is a cure for all these symptoms.
When Alsa returns to previously incorrect device on reboot, then I found it's best to create a config file (~/.asoundrc) to set desired default device
run "cat /proc/asound/cards" to reveal the hardware
tc@box:~$ cat /proc/asound/cards
0 [AK5370 ]: USB-Audio - AK5370
AKM AK5370 at usb-0000:00:14.0-14, full speed
1 [PCH ]: HDA-Intel - HDA Intel PCH
HDA Intel PCH at 0xf7330000 irq 31
2 [NVidia ]: HDA-Intel - HDA NVidia
HDA NVidia at 0xf7080000 irq 17
Here we find ALSA has set a USB Microphone as default playback device (device 0)
To rectify this I use .asoundrc in home directory, which permanently (as long as the rc file is present) sets the default device.
pcm.!default {
type hw
card PCH
}
ctl.!default {
type hw
card PCH
}
Then I use a couple commands run via .Xd to unmute both SPDIF controls
amixer -c 0 cset name='IEC958 Default PCM Playback Switch' on
amixer -c 1 cset name='IEC958 Playback Switch' on
alsa is now configured for the correct device and is un-muted on every boot
I have a road warrior notebook which uses Realtek ALC662 chip and standard notebook speakers, which are configured correctly on boot. Only issue is the Master control always starts muted despite a backed up asound.state file. This can also be rectified with a command via .Xd at boot. using information from aplay -l , amixer controls and cat /proc/asound/cards
amixer set -c 0 Master 60 unmute
with the following
" set -c 0 " = set card 0
" Master " = the control to set
" 60 " = the volume level between 0-64 (AIUI 64 = 100% for this card)
Now with each boot the Master is always unmuted and the volume is set at approximately 92%
Both these tips should be in the wiki