Convert music file from WMA to WAV to MP3:

mplayer -vo null -vc dummy -af resample=44100 -ao pcm:waveheader sourcefilename.wma
lame -m s -V 3 sourcefilenamedump.wav
mv sourcefilenamedump.wav.mp3 filename.mp3
rm sourcefilenamedump.wav

Convert music file from MP3 to WAV:

mpg123 -w destinationfile.wav sourcefile.mp3