I wasn't very clear was I !?
They do attenuate the sound, but when I listened to people demo~ing them, they didn't seem like you could push them at full volume and get virtually no sound coming out, which, like you, was what I was looking for at the time. The one I built, I just put my combo amps in there and blast away. You can hear a little sound but nothing sufficient to disturb. My wife has been working from home in the kitchen for the last 16 months and she doesn't hear it when I use it to record.