can anybody tell me why when i export scenes from BPM sound clearly bad as the original sound quality in BPM i mean the sound on BPM is fuller wich man can hear the stereo effect on it, just after the export sound very thin no stereo fx and so

i tryed to push up the sample rate but no way allways the same result
do i make something wrong ? or its so !!?
"system Mac pro 2010, halo metric and REM sound cards"