These should be fairly simple circuits, but for some reason I can't get my
head around them. Probably do to not knowing what parts out there are
available and what they're called.

First circuit is simple...

My PC has a built in speaker for the soundcard. If I plug
speakers/headphones/etc into the line out port on the PC, the internal
speaker is turned off. Is it possible to keep the internal speaker working
when something is plugged into the line out port? I want to plug in an
extension cable so I can plug headphones into the PC without having to climb
behind my desk. It would be great if the internal speaker were disabled when
I have headphones plugged into the extension cable.

If it matters, this is an integrated SoundMax soundcard on a Dell PC.

Second circuit is a bit more complex...

I have two PC's and one set of quad speakers. One PC has quad output and the
other is just stereo. I plan on building a switchbox that sits on my desk to
control what audio goes where. What I'd like to be able to do is:
- switch the second pair of speakers between the secondary output on PC1
and the stereo output on PC2.
- Plug headphones into a jack on the switchbox and have it disable the
speakers associated with it. There would be a toggle switch to choose
between the front and read of the quad speakers.


Any help out there???