Just found out a solution from Macrumors about how to convert WAV to FLAC with high audio quality on Mac and Windows at WAV to FLAC Converter - How to Convert WAV to FLAC on Mac/Windows?
This solution also helps you convert FLAC to WAV.
It also can convert WAV to Apple Lossless ALAC, M4A, OGG, MP3, AIFF, WMA, DTS, etc.