Splitting analog audio signal
As long as the input impedances of the two "sinks" (destinations) are high enough, and the output impedance of the source is low enough, there is little that you need to consider when splitting analog audio. If the input impedance is too low or your source is high impedance, add a buffer amplifier in between.

Of course, the regular common sense needed when routing noise-sensitive signals applies, but the signals are slow and the requirements of termination/stub management/signal integrity voodoo that are important in high-speed signal routing do not apply here.