Advanced Audio Plugin for UnityInAudio is my audio plugin for Unity and was used for Punish Panda without writting game-specific code. Using a designer-first approach, it is primarily a GUI based system and is fully documented. Among its features is busses, audio ducking, seamless clip playblack and can be used while playing.
Audio design is done via a comprehensive set of designer friendly tools. It can sequence, randomize, loop, delays, etc. among its basic features used a flexible event system to trigger effects. The designer can create event that trigger a variety of things like playblack, volume control, fading, etc.
It also includes a set of tools for music that support synchronized layers and gap-less fading.
It is heavily optimized and can handle several hundred audio sources on a mobile device with a constant 60 fps. To avoid problems with the garbage collector it allocates only a few bytes worth of memory per effect and realies heavily on caching.