(Modified 2013 May 11)
Audio problems
No hardware devices detected by PulseAudio
I attached a new set of speakers, and heard no audio. I heard static from the speakers, which changed when I pulled them in, so I didn't think it was a problem with the speakers themselves.
This particular (X)Ubuntu install used PulseAudio. (My laptop offers a choice of PulseAudio or alsa.) Under the PulseAudo Sound Settings (either from the volume icon in the taskbar or in the Multimedia submenu), there was no hardware device listed under Hardware Output Devices under the Show menu. (The default display is All Output Devices.) There was a listing under Virtal Hardware Devices, which didn't seem right.
I found a solution on the Ubuntu Forums. The steps were to restart PulseAudio with the following commands:
killall pulseaudio (I didn't need the -9 flag, in contrast to the link above)
pactl load-module module-detect (I didn't need to use sudo)
pulseaudio -v (to restart PulseAudio)
Also, I tested the stereo outputs using the webpage Left / Right (Stereo) Sound Test.
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