I have four Streamium products a
MCI500h center with hard disk
WAS7500
WAS6050
and since 4/11/2012 a NP3900
The first three have no problems playing my AAC files, from the MCI500. Other UPNP player like the iPad, iPhone or other devices also play the AAC files, but the NP3900 did not!
It shows the messages format isn't supported!
If I use the Philips app (MyRemote) on my iPad to play MCI500 files on the NP3900, via Simple Share, the NP3900 plays the files without problems!
Only if I try to play the files on the NP3900 direct, I got the error. The files didn't have copy protections, most of them are recorded only via iTunes from CD.
I can't believe that the newest Streamium device is the last usable of my four devices.

Only workaround I found is to recode the data in MP3 format.