The same issue happened on my OS, Ubuntu 16.10, after an upgrade under the utilization of ALSA, Pulseaudio and an external USB Soundcard:
The following measures did not fix the malfunction:
- Disable ACPI in GRUB Boot Options, which could lead to powered off USB Devices: acpi=off
- Disable ACPI in BIOS
- Configuration of Full Speed and High Speed of USB Port
- Configuration files in /etc/asound.conf and ~/.asoundrc as documented by ALSA
- Utilization of pavucontrol
- Reinstallation of Pulseaudio and ALSA Utils
The main issue is the activated IDLE-Mode in the Pulseaudio Config File: /etc/pulse/default.pa that powers off the USB Soundcard.
The following procedure solved the malfunction of the USB-Soundcard:
1. Check available soundcards installed on system.
cat /proc/asound/cards
0 [NVidia ]: HDA-Intel - HDA NVidia
HDA NVidia at 0xfbe78000 irq 21
1 [CI2 ]: USB-Audio - Steinberg CI2
Yamaha Corporation Steinberg CI2 at usb-0000:00:12.0-2, full speed
Index 0: Onboard Soundcard Intel. Index 1: External USB Soundcard
2. Find corresponding driver module for Onboard Soundcard:
lsmod | grep snd
Get detailed info about driver:
modinfo snd_hda_audio
Read description of driver, it should correspond to PCI Card, as discovered in first step, under category "parm".
Note: Driver "snd_usb_audio" is for USB Device soundcards and "snd_hda_audio" for Intel onboard soundcards.
3. Deactivate Onboard Soundcard Driver by blacklisting it, therefore only one audio driver can correspond to the utilized USB soundcard:
sudo nano /etc/modprobe.d/blacklist.conf
Add following line at end of file, by using the driver as eaxmined in Step 2:
blacklist snd_hda_intel
- in my cases the kernel has not to be updated. If the device is not blacklisted in the following step 4, try to update Kernel:
sudo update-initramf -u
4. Check if blacklisting was successfull. Only the second soundcard should appear:
cat /proc/asound/cards
1 [CI2 ]: USB-Audio - Steinberg CI2
Yamaha Corporation Steinberg CI2 at usb-0000:00:12.0-2, full speed
5. Deactivate Idle Mode which is similar to suspend sode for Audio Device, otherwise the USB device disconnects automatically, when no usage by sound application:
sudo nano /etc/pulse/default.pa
Change following line:
load-module module-suspend-on-idle
to
#load-module module-suspend-on-idle
Reboot
Observation: It is recommended to install the application "pavucontrol" for additional configuration and supervising of current sound configurations.
sudo apt-get install pavucontrol
I hope this helps others as well.