My test:
original file.wav, audio CD = 92.3 MB, 1411 kbps
Conversion:
1. Audio CD Extractor (= sound juicer)
file_1.flac = 54.4 MB, 831 kbps
2. ffmpeg without parameters
file_2.flac = 54.3 MB, 830 kbps
3. ffmpeg with bitrate param set to -b 1411K
file_3.flac = 54.3 MB, 830 kbps
Did the conversion to FLAC degrade the original WAV file when all three conversions reduced bitrate from 1411 to 830 ?