What would be more effective around round duct for sound proofing 1" duct liner or mass loaded vinyl? The room will be approx 20X25 and all the round ducts that lead to the second floor is located within the room as well as the main supply & return. I was thinking of wraping the round ducts with duct liner. The mlv would be more expensive than duct liner. Also I'm using a drop ceiling and insulating the joists with r-19 or r-30.