How to redirect sound to USB headset when plugged in?

If you want to manually move the audio, you can do so in the Control Panel. Here are instructions:

  1. Right-click on the volume icon and choose playback devices
  2. Right-click on the device you want audio going to and choose Set As Default Device

That's it. Audio will now route there immediately. Note that this is new to Windows 7 and won't work on Vista or XP.

Note: if you are using Windows 7 (which your tags seem to indicate you are), I would have thought it should work regardless. Windows 7 adds a new feature to route the audio on the fly to a newly arriving device like a USB headset. Likewise, when you unplug the headset, the audio will re-route to the last device it was playing on.

I have a USB PLantronics headset and I have to make sure it's chosen as the default playback device before starting any games. Like this:

Right click the speaker icon in the tray. Choose Playback Devices. Click the headset and then click the Set as Default button.

After that games will normally use the default playback device.

This depends completely on both the application and sound card.

Generally speaking, applications can "request" sound on a certain device, (and give you the option to change devices).

Games on the other hand requests sound when they start running (through DirectX) and then keep playing through it. In some games you can restart the sound system by changing sound settings in-game, such as if the game offers 3d sound, or any sort of "advanced" effect, however generally speaking, volume alone does not do this.

The best alternative that is guaranteed to work is to get a speaker with a headset port as the moment you plug in a headset, the speakers will output to it. Unfortunately for you, I have never seen one with a USB headset socket.