I've never used FLAC files before so I had to hunt around for something to play them. Winamp does, so I'm using that, though I've never been too keen on it.
I've been looking at MediaMonkey, since this has been recommended on this forum before, but I've discovered that it doesn't support ATRAC3plus, the Sony format, and I've got a lot of those on my PC, items imported from minidiscs. Windows Media Player
will play them however (and SonicStage of course). So it looks as if I'll have to continue using different software for different codecs
Audacity supports FLAC importing (as it should) but you don't seem to be able to save in this format.