From Keerby Application:
Convert all your music files on your android device
All major input formats supported as Mp3, Flac, Wma, Ogg, Aac, Ac3, Ape, Wav, aiff.
Configure entirely the output format with customizable frequency, bitrate, channel, time start and duration (for part selection) (inApp purchase to unlock highest quality settings).
Example supported conversion:
Convert Wma to Mp3, Wma to Aac;
Convert Mp3 to Aac, Mp3 to Wma;
Convert AAC to Mp3, AAC to Wma;
Convert Flac to Mp3, Flac to Aac.