Unity 5, MP3 hardware decoding on IOS

Can someone please tell which audio file property (or properties) I need to set in Unity 5 in order to have that file decoded on hardware on IOS devices?

In Unity 4.x there used to be the IOS specific "hardware decoding" switch, but on Unity 5 this is now replaced with the platform overrides (definitely better). So is using IOS hw decoding now simply about using some specific setting (eg. "Compressed in memory") or perhaps some combination after enabling 'Override for iPhone', eg. setting Compression Format to 'MP3' & Load Type to 'Streaming'?

IOS devices can of course decode only one stream on hardware, so hw decode won't work for crossfading music etc. However it would be neat to offload some assets that don't require crossfading to hw.

I've searched through both Unity & forums but found no answer this. It would be great to see the Unity manual covering this topic either under Audio or Platform Specific / IOS section.