WaveLab FLAC compression ratios vs. other encoders

After reading a couple notes on other forums, I was curious to test…

I just used the batch converter in WaveLab to convert an .mp3 to FLAC (compression level 8). Original file was 4,960kb and the resulting file was 37,130kb.

Then I encoded the same .mp3 file with other tools, with the following results:
XRECODE 3: 21,747kb
dBpoweramp: 21,835kb
MusicBee: 21,790kb

So obviously the general-market tools are achieving a ~40% FLAC compression advantage over WaveLab’s FLAC compressor, using the exact same setting of FLAC level 8. Any ideas why?

Wavelab is using an old version of the FLAC encoder, but the difference in file size shouldn’t be this huge. Try forcing Wavelab to output a 16 bit file and see what happens.