Engadget explains the difference between two commonly confused Dolby surround sound formats found on TVs, streaming devices and home cinema equipment. Dolby Digital (also called AC-3) is the older standard, capable of carrying up to 5.1 channels of audio, while Dolby Digital Plus (E-AC-3) is a newer, more capable format that supports up to 7.1 channels and can also carry Dolby Atmos. However, the "Plus" naming can be misleading, as Dolby Digital Plus does not always deliver more channels or better sound, it simply has the capacity to do so when the source material supports it.

The article breaks down what channel numbers mean, with the ".1" referring to a dedicated low-frequency subwoofer channel, and explains that both formats use lossy compression, unlike the lossless Dolby TrueHD used with Atmos on Blu-ray discs. Dolby Digital Plus was designed with streaming in mind and is used by services such as Netflix, thanks to its efficient compression and multichannel support. The piece advises that users with modern, compatible equipment should leave Dolby Digital Plus enabled, since it can handle standard 5.1 audio as well as 7.1 or Atmos when available, while only reverting to standard Dolby Digital is necessary when connecting to older hardware that cannot decode the newer DD+ bitstream directly.