Problem with my sound card !

hey guys ! i got the Asus Ex-58 EXTREME RAMPAGE II motherboard ! with the Supreme Fx- X-Fi sound card ! recently ive seen some problems with 2 things :
first of all a minor trouble and i just want to know if its a big problem or just a past time event and didnt damage the Soundcard !
i was trying to get my friends to play some music for them so i needed the Sterio mix option in Windows 7 ! anyway i kept playing with the sound options ! till i finally found it ! anyway i changed the default format i changed it from 16 Bit , 44100 Hz CD Quality to 24 Bit 192000 Hz Studio Quality !
and the other options werent the same once and then the same options what happened is after 5 seconds from pressing Ok ! i heard a booming sound ! and when i shuted down this option the booming sound stopped ! i want to know what did ive made wrong ? second of all whats my mistake and how to avoid it and how to use the 24 Bit without having any problems !
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second of all : I got a problem with the Sound Buster program when i installed it on my prev. windows XP 32 Bit ! it showed a required Serial Key ! i found the CD key on the CD ticket however it always kept saying this S.K Is not valid ! i didnt know what to do ! can someone explain to me why this problem is taking place ? becuz im worried !