There is no difference. One can easily find this by examining the WAV files via their spectrums. There are plenty of software packages for this. In the end, so long as the compression algorithm is doing its job, there is absolutely NO difference.
As for batch processing the standard among OCD folks like myself is dbPoweramp or using FLAC->WAV in Foobar2000.
As for batch processing the standard among OCD folks like myself is dbPoweramp or using FLAC->WAV in Foobar2000.