This app was mentioned in
with an average of
You can use the Audio Buffer Size app to find the native settings for your device... But it's probably not worth the effort of re-sampling your library unless you have specific files that won't play, in which case be sure to use a decent re-sampler like sox or at least a good frontend for it e.g. foobar2000 with the appropriate plugin.
I'm not sure if you can change anything in the system without getting deep into the rom itself, that said I read that Android L supports 96khz... whether that's implemented or not for the Moto X it doesn't look like it.
I used [link] to run a test and it shows me at 48khz.
Sounds like they may not support 48. Drop down to 41 and retest. If they all of a sudden start to work, your gun should be smoking. If they're android, try this [link] it helps to see if the device natively supports 41 or 48.