A search of the web brought up this page:
"Convert Mac WMA audio files to MP3?" from the Ask Dave Taylor! Tech Support Blog
This guy claims that what we're trying to do works. I have submitted the comment below:
A closer look at the FAQ for switch suggests that wma conversion only works in the Windows version of this app:
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Q. What file formats does the converter support?
Switch can open files in the following formats:
* wav (PCM, ADPCM, aLaw, uLaw, and others, see here)
* mp3 (MPEG Layer 3)
* au
* aif/aiff
* gsm
* vox
* raw
* ogg
* flac
* aac*
* m4a*
* mp2 (MPEG Layer 2)
* wma*+
* rm / ra / ram+
* dvf (Not all dvf recorders are supported)+
* msv (Not all msv recorders are supported)+
* dss (SP Mode only)+
* cda+
* .mov !
* .amr !
*Copy protected files are not decoded
+ Windows only
! Mac OS X only
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Would like to have this confirmed by someone who knows more though...!