Hello.
It is not recommended to convert from one lossy format to another. And what about converting from LossyWav to another lossy format (e.g. Ogg Vorbis)?
Since lossywav keeps a clean signal path, It is expected to transcode very well using setting -P or more. I found some negative interaction with noise shaping when transcoding to mp3 and that has been fixed it the latest release.
See this thread (http://www.hydrogenaudio.org/forums/index.php?showtopic=79372).