I found this unfavorable remark about the codec used by iSonics: 'Contrary to libavcodec's video codecs, its audio codecs do not make a wise usage of the bits they are given as they lack some minimal psychoacoustic model (if at all) which most other codec implementations feature.' It also seems to be an inferior codec to the libFLAC codec that XLD uses. Who knows what algorithms they use to compress at additional levels? Therefore it seems iSonics uses a codec that does not adhere to FLAC standards. If libavcodec wants to call its 12 levels FLAC then the developers should attempt to have the FLAC standard amended. Since libavcodec uses compression levels other than the 8 approved levels, they should not be called FLAC, they should be called FLAC Plus, or some other name that differentiates them from FLAC because they aren't technically FLAC. Put simply, levels 9 to 12 use additional or alternative settings to achieve better compression.' I received this reply: 'Levels 0 to 8 use essentially the same compression settings as the official libFLAC encoder. When I asked the developer why, they were rather blunt and told to me to ask the developer of the libavcodec that they use. The FLAC standard only has 8 approved compression levels.

Xld download for mac