Hi. Whatever the input file is, whether ape aac m4a, pick the matching decoder from the codec drop down box.I don't use this frontend but the screenshots suggest this might work. pick an output directory and activate.
There is no wav codec. Codecs take wav files and convert them to smaller representations of the wavs that try to sound the same through perceptual and huffman processing etc.The codecs (COmpression & DECompression) then can decode back to wav.
Nero has an aac codec as does itunes.The m4a extension is a form of aac encoding.Try the AAC forum.Faac is a free aac encoder.Itunes is free too and I think tests show higher quality.
Most any media player will handle a 16/44 wav
You should try reading the FAQ first though. You have some gaps in your information base.
http://www.hydrogenaudio.org/forums/index.php?showtopic=7516