Is there a way to use the audio line out from the motherboard (or and sound card) and also to signal audio out to a pair of smaller speakers which are connected via USB at the same time.
Windows only gives you the option to choose one audio device for audio out and audio in.
How can I use two devices for playback at the same time?
no, you can't. if you did a little research you could read about this.
http://www.tomshardware.com/forum/364355-28-playing-separate-audio-sources-separate-devices
From my understanding this was an attempt to limit a normal user from being able to record audio from Media such as Blu-Ray or DVD Disks, was enforced by Sony after a conversation with ASUS Tech Support, the links above have people claim it's a windows limitation. Either way, can't be done.
Yes, you can run multiple audio streams at the same time. I have a couple of these on my system. One the built in sound port. Another my usb headset. And still another, and even more interesting, is a fire-wire connected audio interface box with two microphone inputs and 8 audio outputs. All of these audio streams can run at the same time with appropriate software, and with enough CPU horsepower and a fast enough disk, and sometimes by shutting down other interfering software. They sell all sorts of hardware and software that does this for the recording of music so that people can set up a home recording studio and run it all from a laptop.
When you add an additional piece of hardware such as the USB speakers you mention an audio driver is often, but not always, added to your system. Sometimes a built in driver is used. In any event an appropriate piece of software can then access that driver with a separate stream of audio, independent from the normal audio stream that feeds your built in audio interface. Take yahoo chat for example. You can be using your USB headset and talking to someone and at the same time listening to music from your speakers, and they are two different streams of audio.
