after numerous days trying to workout what the problem is i have realised now i just need advice on the best setup method

my sx 2 is set to full duplex and as far as i am aware i thought it was setup right but when i play the track in sequencer no matter if midi or wav or what track it is after a while it crackles...

aft first ot was crackling very bad most ofthetimebut messing around in the device set andthe aiso multimedia setup and full duplex setup i have managed to make it crackle less but not stop it completely.....

i have an m-audio ozone with the built in soundcard does anyone know the correct or best way to set it up with cubase sx 2


i.e what the best sync refrence setup is....if you start input 1st or output first.....

i would really appreciate any help