I am looking for a dead silent to nearly silent return pump that pushes 550gph at 4ft of head pressure. I am having nothing but issues with my sicce syncra sdc 6 and can hear it through the floor and walls. The pump is not touching anything in the sump. I expected the sicce would be quiet, but at 29% the pump db is 57db. Sicce is sending a new impeller in hopes that resolves the issue. If not, I want to start researching other options.