A:Answer Yes, this works with optical digital input. It also works with ARC, which allows you to transmit sound from the TV to the receiver via an HDMI cable. You can pick which ever one you want or allow the choose automatically, which I believe is the default settings (you don't have to change anything to choose this one).
ATMOS is a Dolby surround sound technology that replaces up to 4 of the surround speakers with height speakers. In the case of the TX-SR393, which supports only 5.2 surround sound (5 speakers with 2 subwoofers), you can turn it into a 3.2.2 system if you like (3.2.2 means 3 speakers--Left, Right, Center--plus up to 2 subwoofers plus 2 Dolby ATMOS height speakers). The ATMOS effect is to make things like rain sound like it is falling from overhead. To utilize this, you need to either mount speakers high (on the ceiling or high on a wall) or have ATMOS-enabled speakers, which have an extra speaker built into each unit that faces the ceiling, allowing sound to bounce off the ceiling to create an effect of sound falling from above.
