What is the best way to combine two audio sources into a single audio output? A friend and I are looking to start a podcast, yea, just like everyone else on the Internet. 

We are trying to determine the most practical way to combine two audio sources into a single audio output of not necessarily production quality. The combined audio will not be recorded, and used only for communication purposes. It is our intention to record our own independent tracks at different locations, and later combine them in post.

Our setup is to include a PC at each end with either skype/hangouts, audacity, a USB microphones, and a set of earphones each. The PCs will be used to record audio from our USB microphones, and to establish a line of communication between sites. How can we reasonably combine the audio out of a microphone (with a 3.5 mm and/or XLR) with the audio out of a PC (3.5 mm) so that we can hear both ourselves and the other person(s) in the skype/hangout meeting?
I misspoke in my original question, I've fixed the sentence so
  hopefully it should be clearer. I'm just wanting to listen to the PC
  out, while simultaneously listing to the Mic out as I record it.


If you using Windows, then just go to the

 Sound (Right click in notification area) > Recording devices > Chose you device > Properties > Listen > Listen to your device

That would allow you to hear your recording device input in your playback device(speaker).