I currently have my S4 connected to my I Mac, I’m a bit of a newbie, although i did connect it a while a go, when the volume is low i can here a buzzing noise through my speakers (5 inch Rokits) I remember that when i connected it routing the sound took me ages. please help.
You need to check if the cables you’re using a balanced - the type of shielding that surrounds them, it might say on them, it might not! Try some grounded cables though to rule that out - sounds like the issue to me.