Questioning FLAC Audio benefits Larger Size & Lower Volume

[raulduke]

I was trying an experiment after switching over to FLAC I noticed that I was having to turn up my amplifier a lot higher than I ever normally do (-9 and higher) since I started using the FLAC option. So I tried 2 encodes of "The Adventures of Baron Munchhausen"

Using a digital db meter there seemed to be a difference in volume of a few db the FLAC was a little bit lower volume. I looked at the audio information in VLC and my Yamaha amp about the 2 different files.

Dolby True HD 48kHz 3/2/0.1 dialog +4
FLAC 48kHz 3/2/0.1 dialog 0 (nothing displayed)

after all this I looked at the file sizes and found the FLAC file was larger than the True Dolby

FLAC 27.98 GB DOLBYTRUEHD 27.01 GB

At this point I'm wondering if this is a fluke ?
Shouldn't the FLAC compression reduce the size
I guess the +4 for dialogue might be done by the amp when it senses True Dolby and adds the +4 and doesn't when it's just PCM (is this setting in the the flag ?)

I was wondering if anyone else has also had volume and data size weirdness as well as me

Maybe 32 bits doesn't compress in FLAC

[Romansh]

TrueHD and DTS-HD are already compressed. If your playback setup supports DTS-HD and TrueHD, don't bother. The file size savings will be minimal (though you will save a few hundred MB on some of them), and you'll lose some medatata (dialnorm, drc, downmix matrices).

FLAC is more interesting when the source is LPCM (the space savings will be a bit more significant), else if your playback setup doesn't support either of DTS-HD or TrueHD.