Example of the sound quality you can get out of this:
Step 1: What you'll need
2 Male RCA to Female 3.5mm Adapters:
2 3.5mm Microphones:
As user Rogue Agent pointed out in the comments, you should take a look at the frequency range of the microphones you're buying. The ones I linked to are made for voice recording, so they aren't the best for recording music/sound. Human hearing range is about 20Hz - 20kHz, so microphones closer to that range would work better.