Well, i looked for information about this speaker on Philips website, they say that audio input is via audio jack or bluetooth.
According to their documentation, the micro USB port is only used for charging.
So i guess your audio might not actually go through USB.
If for some reason you need to listen music via USB, i would suggest using one of the 2 soundcards that were successfully tested with the FP2 by the community :
Audio
- PCM2704-powered sound-card
Reported by @retsifp. At least 3.5mm output works, and the three buttons (vol +/-, mute) are active.
TOSLINK and S/PDIF outputs untested, but likely to work.
- HiFime DIY 9018D