I have only done one. Countertop to ceiling mirror, tv appearring in the middle. More than one wall was mirrored and you could see a slight difference between the wall with the two way and the standard mirrored walls. Just an FYI.

As far as sound... It was a parade house, so initially the builder didn't want sound (extra money). When the house sold the homeowner chopped the bathroom tv sound out of the quote, I had quoted a niles piece, amp with AB auto switching between whole house audio and tv.