Sound quality problem

hi everyone , me and my friend dj jack download from the beatport.com mp3 tracks he gets a excellent quality and i don't   ,,,,, the only difference between us is that his MAC is connected to a m-audio sound card and a small stereo system , but i am not....... i only use the original MAC function , we both use the same kind of external CD burners and same CD quality..

do the track quality get effected when downloading if the computer is using or not using sound card ??
he send me tracks from time to time i burn his tracks and i buy the same tracks and download them and listen to them , well, his tracks with more surrounding and nice treble etc ,min, r with strong bass and sharp treble etc ??? any body please tell me what shall i do or what is the problem

i tried to burn a CD from a computer that have no sound card inside and the CD was burned but it was empty