I'm pretty sure it uses PS-ADPCM but I cannot work out how to separate the individual files.
These two .bnk files were separate from the main .qrk archive.
There are filenames inside these bnk files and all I have managed to work out from these two is that the total number of files is found at offset 0x37.
I'm not sure where the interleave offset/s are stored and I'd like to know how I could work out the size of each of the audio streams of each file.
Example 1
Example 2