I think most just use a simple mouse pad for vibration damping. However, if the pump is making a noise and running rough from being choked down. Then it won't be long before it doesn't work. IMO, you need to figure out why the drain is noisy.
So, how is it plumbed?
How many 90's, 45's,ect.
If you have a ball valve on the drain that will restrict it alot right there causing a back up of water. It breaks up the laminar flow