So it appears that including a stream from disk audio file in an Asset Bundle is a big memory hog. It looks like the whole track is loaded into memory uncompressed.
The answer is to compress music in memory and to avoid direct references in the scenes, rather load them from an individual track bundle when needed.
Thanks for posting this Mike - hugely helpful when I was debugging iOS audio usage this weekend.
It seems that even without AssetBundles, using Stream From Disc on iOS is dangerous with short clips. I have just verified (both with Unity’s profiler and Xcode) that if you have lots of short clips (like dialog), and select to stream them in from disc, you then get a single disproportionately large alloc, which shows up in the Unity memory profiler under Assets/AudioManager.
I currently have dialog totalling around 8Mb in a scene, and if I set all of it to “Compressed in Memory”, then I get a 5.4Mb AudioManager allocation, plus the size of the compressed dialog under Assets/AudioClip. If I set it to “Stream from disc”, then I get a ~64kb alloc per audio sample (presumably some header), plus a 15Mb audioManager alloc. The resulting ~10Mb difference between the two builds can be easily measured using Instruments’ Activity Monitor.