Can I use an optical audio splitter to connect my Apple TV and cable box to 1 surround sound receiver input?

I have an HD cable box connected to the only optical audio input on my surround sound receiver. Is there an adapter/splitter that I can plug into the input of the receiver that will allow me to connect both the cable box and my Apple TV? I searched online and found a splitter, sort of a Y-adapter, but it looks like it has female connections on all 3 ends. The description says it has 1 input and 2 outputs...wouldn't I need something with 2 inputs and 1 output? Or does it matter...could I just as well connect both devices to the adapter, and use a 3rd optical cable to connect the adapter to the receiver? I just don't want to spend the money if it's not going to work. Thanks!