That's a serious amount of kit, and there's no way 20+ machines isn't going to emit a constant roar. At some point, if you're going to have that kind of setup,

That's a serious amount of kit, and there's no way 20+ machines isn't going to emit a constant roar. At some point, if you're going to have that kind of setup, it needs to be in a dedicated workshop that's either free-standing, or somehow otherwise sound-isolated from the main house. I know I'd never get away with running that much equipment all at once!