And... since the cinema6/7 learning remoted can have a macro assigned to just about any key, you could conceivably have one press of the MUTE button mute all (OK, only 15) TVs. The macro feature has a limit of 15 button presses, but if you're standing near at least ONE TV, then manuall press the mute button on it.

Then again, a Pronto could do this in a flash. Any button on a pronto can have up to 255 actions assigned to it. You can put as many different buttons on a single touch screen panel as will fit, and there are several hard buttons including mute, vol-up and vol-dn. It's not cheap compared to a Cinema, but if it does the job...

Dave