Sound from my Hanspree Xm-S monitor.

Sound like you need a audio switch. I have 2 of them, and both have worked great.

This is the one, I have, but they are very hard to get now.
http://tinyurl.com/279g23

This is a different one, but works ok. It just did not have the features like the first one.
http://tinyurl.com/ys2f9g

With the audio switch, or audio hub, as the first one is called. You can direct audio to your speakers or a pair of headphones.
I like the first one, because I can mute both, and the mic and adjust the volume. As I said more features. The second is just a toggle switch to send the audio signal to the speakers or the headphones.