The quality parameter for FLAC refers to the quality of compression, not audio. The audio will stay lossless but you get a better compression with higher quality. Higher quality will take more time to compress however.
See docs http://wiki.jriver.com/index.php/Encoding_Settings
Free Lossless Audio Codec (FLAC): FLAC is a popular lossless, freely available open source encoder. [2] Quality Settings: 0 - 8. Sets the quality of compression (and not sound, which is lossless), 8 meaning most compressed/time/effort.