The 400 is reduculously quite. I had one and it was the quietest gun I’ve ever owned. Always gave the impression that it was lower power than what it was which I always shot at 30+ for.
My Crown is a 25 so it’s definetly louder than a 400.
The Crown with the shroud extended is pretty quite as well. I ended up putting the shroud off my 500 on my Crown. It’s as quite as the Crown with the shroud extended without all the possible movement.