Used AC3Machine to convert WAV to AC3 but the volume seems lower

[Carlos Menem]

I pretty much used default options only changing the bitrage from 224 to 384 as is recommended for 5.1 but I then compared both audios and the wav sounds louder then the ac3 I didn't try to listen for other variances... Also the ac3 file is smaller in size...
Do you know more optimized settings I can do to have closer quality playback? Also powerdvd doesn't keep good track of timming for the ac3...