To update you guys, I think I've determined the cause of the whining hiss. I managed to get a hold of a used OEM Professional radio from a fellow forum member and it seems that the whining/hissing noise is completely gone.
I would carry on using this radio, but it seems like it doesn't support 6FL (no USB icon appears on the screen). I guess that means I have to get a 'new' radio from BMW. I say 'new' because it appears that BMW doesn't sell brand new radios, but only remanufactured ones. And they run about $800 before a $500 refundable core.
Please correct me if I'm mistaken. Anyone know why they don't sell 'brand new' radios? One more thing, if I put in a 2009+ LCI radio, will any extra coding be needed, or would it just be plug-and-play?