Default [Q] Where does Amazon Music store downloaded Prime music?

So Amazon Music now allows Prime members to download free Prime music to their mobile device for offline listening. Anyone know where on the device they store this music? If they're putting it on my phone instead of its external SD card, I'm going to be much more conservative about how much Prime music I download. Obviously they have security measures to keep the Prime music from being freely accessed outside of the Amazon Music App (and thus possibly shared), but something has to be stored somewhere... I just want to know where, exactly.

Apologies if this is a stupid question.

Using a rooted Sprint Samsung Galaxy S5, stock ROM (for now)