Is the output object based or channel based? If it is object based, how many objects can it generate concurrently. If it is channel based, what channel formats are supported, mono/stereo/5.1/7.1? Anything else?
If I understood your question correctly:
-
Unity supports mono, stereo and multichannel audio assets (up to eight channels) [e.g. mono/stereo/5.1/7.1]. More about supported audio formats you can read THERE.
-
Output is based on Audio Source position, its settings and Audio Listener position (usually main camera). You can also prioritize certain audio sources in their settings, so that your music or narrator will be surely heard.
-
Maximum number of audio sources playing at once depends on Audio Manager settings as well as hardware capabilities.
And if that wasn’t enough there are plenty of other things you can read, in documentation, about audio capabilities, for example Audio Mixer.