I've spent a couple of days looking for a solution with no results, so I hope to find here someone expert enough to point me in the right direction.
A lot of people faced the same issue I have, but they appear to have different circumstances due to the different Raspian distro, which is often referred to be Wheezy while I'm using Jessie.
My aim is to configure my USB audio device as the default one, both for the speakers and for the microphone.
All the info that I was able to find was referring to those steps:
1. check for the device to be correctly hooked up & recognized by the OS (using dmesg, lsusb, aplay -l, etc).
2. edit the "/etc/modprobe.d/alsa-base.conf" file in order to indexing the USB audio device before the built-in one.
3. edit the "~/.asoundrc" file to make the USB Device as the default device.
Step 1
The system is able to see my USB Audio device as you can see in the following outputs:
Code: Select all
pi@raspberrypi ~ $ dmesg | grep C-Media
[ 3.361759] usb 1-1.4: Manufacturer: C-Media Electronics Inc.
[ 3.394557] input: C-Media Electronics Inc. USB PnP Sound Device as /devices/platform/soc/20980000.usb/usb1/1-1/1-1.4/1-1.4:1.3/0003:0D8C:013C.0001/input/input0
[ 3.480118] hid-generic 0003:0D8C:013C.0001: input,hidraw0: USB HID v1.00 Device [C-Media Electronics Inc. USB PnP Sound Device] on usb-20980000.usb-1.4/input3
Code: Select all
pi@raspberrypi ~ $ lsusb
Bus 001 Device 005: ID 2001:3308 D-Link Corp. DWA-121 802.11n Wireless N 150 Pico Adapter [Realtek RTL8188CUS]
Bus 001 Device 004: ID 0d8c:013c C-Media Electronics, Inc. CM108 Audio Controller
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. SMSC9512/9514 Fast Ethernet Adapter
Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Code: Select all
pi@raspberrypi ~ $ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: ALSA [bcm2835 ALSA], device 0: bcm2835 ALSA [bcm2835 ALSA]
Subdevices: 8/8
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
Subdevice #4: subdevice #4
Subdevice #5: subdevice #5
Subdevice #6: subdevice #6
Subdevice #7: subdevice #7
card 0: ALSA [bcm2835 ALSA], device 1: bcm2835 ALSA [bcm2835 IEC958/HDMI]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: Device [USB PnP Sound Device], device 0: USB Audio [USB Audio]
Subdevices: 1/1
Subdevice #0: subdevice #0
Here starts my troubles since I'm unable to find the "/etc/modprobe.d/alsa-base.conf" file... moreover I can't figure out how I can create my own alsa-base.conf file because every example I found are related to Raspbian Wheezy and they includes settings for the built-in audio device.
Step 3.
My .asoundrc contains:
Code: Select all
pi@raspberrypi ~ $ cat .asoundrc
pcm.!default {
type hw
card 0
}
ctl.!default {
type hw
card 0
}
Moreover the .asoundrc seems to be restored to its original state on each boot.
I'm very confused about all that and I can't find a complete yet concise technical documentation about devices and alsa configuration.
I believe there are a lot of stuff which I'm not aware or conscious of...
Hope someone could help me in someways.

Thanks,
Paolo.