Flac is broken for me too using 1.90.1. "Audio format not supported" on my PS3.
Tried the config changes mentioned but no luck.
Tried 1.81.0 and 1.80.0 and same problem on these versions
Very sad, most of my media library is on flac.
Rolling back to 1.52.0 (works fine there)
Running on Win 7 (64 bit) & PS3.