I've been playing the RealMedia .ra encodes using my Xcard (yep it can play these files too!). I noticed the disortion when comparing the rips ones I made using dbPowerAMP.
I've posted some links to the files here: -
Created_using_RealMedia_AAC@96kbps.ra
Created_using_dbPowerAmp_AAC@96kbps.mp4
It might well be just an Xcard thing.
Cheers