Back in the days, I bought a Creative Inspire 5100 speaker set for cheap. I used it with my desktop who had a 5.1 sound card (PCI). Then a used it with with my laptop who had an external sound card Hercules Muse Pocket USB 5.1. It had always worked very well and the quality of sound wasn't so bad in my room.
A few months ago, I switched to Mac and bought a Macbook. The problem was that the external sound card wasn't supported by Mac OS. I found some cheap '"Y'' Audio Splitter at the dollar store and bought 3 of them, but the setup wasn't very cool and worked like sh*t !
I finally decided to build something to solve my problem.
I wanted to have a box with 2 Inputs (MP3 or Macbook), a switch (inverser) to select the input I needed, and 3 Outputs to connect the speakers.
Step 1: Material
The inputs must be 2 X 2 panel mount RCA jack,
the outputs must be 3 X panel mount 1/8" panel mount stereo jack,
and the switch/inverser must be a ON/ON type,
and a case !
for the case, I decided to use an Altoid case but it's not a good choice ! In fact, you cannot use a metal case if you want to have 2 Inputs, I realized it too late, so I have only one input.
Step 2: Circuit ( 1 Input)
I had two different type of stereo jack connector, the principal thing to do is to know where to connect the Ground, the Left and the Right signal.
Then, you have to connect ALL the Ground together, ALL the Left and ALL the Right signals together to the RCA connector.
Step 3: Circuit ( 2 Inputs)
Here is he part where you will need the switch-inversor, with it, you will be able to open or close the circuit by connecting or disconnecting the Ground.
Remember: Use a plastic box ! Most of the connector has the Ground connected to the external body, if you use a metal box (altoid), all the masses will be connected together and you won't be able to open the circuit you don't want to use.
Step 4: DONE !
now it's time to try it !
connect everything and KICK ME SOME BASS !