I've found that if these MagDrive submersible pumps are resting against the bottom of the sump, or leaning against a wall of the sump or anything else in the area, the sound of them humming can be quite loud. Sort of amplified the noise in my sump, stand and floor.
Not sure if you are using vinyl hose, tubing, or rigid pvc pipe for your return, but in any case, if possible see if you can suspend the pump off the floor of the sump and inch or so. Sort of let it hang there by the return line or ball valve, or whatever you have there. This allowed mine to run much more quiet.
Try it if you're interested - it's free