Avids are a bit fiddly to set up and the “tri-align” washer system is a faff but, with time, you can usually get the to run silent – loosen the bolts, wiggle everything around, pull the brake lever a few times then hold on & carefully tighten the bolts up again. It can take a few attempts.
Having said that, they do run close to the rotors so aren’t very tolerant of warped discs.