If you already own a 5.1 or 7.1 AV receiver-based wired surround sound system, you can keep all of your existing speakers, and then upgrade your system with a Dolby Atmos AV receiver and some ...

Dolby Pro Logic was introduced shortly after for playback of the center channel as well. Pro Logic II added left and right surround channels (5.1), and Pro Logic IIx added support for 6.1 and 7.1 ...