I have a vertical tube in the overflow, that goes almost to the waterline.
It goes straight into the bulkhead.
At the very bottom of the tube, I drilled a big hole. I then put a slightly larger pipe section loose around it.
So by moving the larger pipe section, I can change the flow through the hole.
I adjust it so that 90% of the water goes through the bottom.
But enough goes through the top, such that the overflow fills up slowly, and trickles down the full tube.
I do get air sucked in, but it mixes way down at the bottom of the tube, so you cannot hear it.
But that also means it is not in full siphon, so you don't get the "flush" effect.
In a way, it is like a Durso, but with an extra inner valve.
HOWEVER: My sump is not much lower than the bottom of the tank, since it is in the garage.
I am not sure my method would work on a more normal setup.