Ubuntu 18.04 Usb audio device suspended

For Ubuntu 16.04+

Install TLP and list USB Devices

The port for your sound device is auto-suspended when it is idle. The TLP package is the easiest way to manage this. Use these commands:

sudo apt install tlp
sudo lsusb

tlp may all ready be installed in which case you will see:

tlp is already the newest version (0.8-1).

lsusb will list all your USB devices:

Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 003: ID 2109:0812 VIA Labs, Inc. VL812 Hub
Bus 002 Device 002: ID 2109:0812 VIA Labs, Inc. VL812 Hub
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 009: ID 046d:c52b Logitech, Inc. Unifying Receiver
Bus 001 Device 007: ID 1bcf:2b8c Sunplus Innovation Technology Inc. 
Bus 001 Device 005: ID 0cf3:e301 Atheros Communications, Inc. 
Bus 001 Device 003: ID 187c:0528 Alienware Corporation 
Bus 001 Device 010: ID 413c:9016 Dell Computer Corp. 
Bus 001 Device 008: ID 2109:2812 VIA Labs, Inc. VL812 Hub
Bus 001 Device 006: ID 0764:0501 Cyber Power System, Inc. CP1500 AVR UPS
Bus 001 Device 004: ID 04f9:024a Brother Industries, Ltd 
Bus 001 Device 002: ID 2109:2812 VIA Labs, Inc. VL812 Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Find your specific USB device

Find your sound device in the output. For example my wireless keyboard/mouse is:

Bus 001 Device 009: ID 046d:c52b Logitech, Inc. Unifying Receiver

The important details here are the Manufacturer's ID followed by a : and then the Model Number. So I want 046d:c52b. Find the equivalent for your sound device.

Blacklist your USB device from auto-suspending

Open the TLP configuration file using gedit:

sudo -H gedit /etc/default/tlp

Search for these lines in the middle of the file:

# Exclude listed devices from USB autosuspend (separate with spaces).
# Use lsusb to get the ids.
# Note: input devices (usbhid) are excluded automatically (see below)
#USB_BLACKLIST="1111:2222 3333:4444"

In my configuration file I have nothing blacklisted. A line beginning with # is a comment and ignored in all configuration files. Note it says **(usbhid) are excluded automatically**.hid` stands for Human Interface Device which includes my keyboard and mouse but excludes your sound device.

So we want to add your sound device to the file. Insert the line immediately below the four listed above:

USB_BLACKLIST="046d:c52b"

IMPORTANT: Change 046d:c52b representing my keyboard/mouse to what you found for your sound device.

Now save the configuration file, exit gedit, save all your work and reboot.

Credit: How can I disable usb-autosuspend for a specific device?