Yosemite : change sound output between speaker and headphone
8143
Use internal speakers with others plugged into headphones jack
65101
Can audio go to both the speakers and a bluetooth headset simultaneously
5243
Using wired and wireless headphones simultaneously?
1171
Multiple Bluetooth speakers simultaneously
109898
Is it possible to use USB output and audio port output at the same time?
38492
Change Windows sound volume via the command line
149864
Controlling Volume Mixer
54876
Stop making iPhone constantly change sound volume on its own?
86347
Why can't I use my internal microphone at the same time as my headphones?
104806
Xubuntu - how to use both front and rear audio output?
31152
Mono jack output to stereo headphones : how to send the mono signal to both sides?
158151
How can I lower the volume of my USB headphones?
101041
Is it possible to use the laptop's audio via headphone jack and Bluetooth speakers at the same time?
105584
How can I play a custom sound when my battery is low?
45677
Routing Applications sound to different sound device? (Windows)
27308
How can I change the default audio device from command line?
8983
How can I easily switch audio output in Ubuntu 17.10 and later with GNOME?