It says it doesn't support 5.1 output, only 2.0 output, via optical output. That's why he specifically mentioned "receiver" and "multi-channel inputs." Dolby Headphone or any other surround sound simulation is a 2.0 channel signal. The key word is simulation. If it was a true 5.1 signal then even if it manages to get out of a soundcard and play through a stereo headphone system you'll hear Front Left and Front Right with no Surround Left, Surround Right, Center, nor Sub (a stereo DAC will not even begin to decode a 5.1 signal - that's like trying to talk to somebody in a totally incomprehensible version of a language he knows, like a 2017 American talking to some 10th C Saxon King in England). The 5.1 signal that goes into the soundcard is reprocessed into a 2ch signal for surround sound virtualization. Unlike regular downmixing on most HT receivers virtual surround adds reverb since it's not just plain downmixing, it's virtualizing space, it's just that hardware limitations - not simply due to two physical channels, but that they're smack outside the listener's ears - can't allow simulating for the exact same soundscape (speakers 5ft from you in real physical surround won't sound like gunshots are coming from 100yards away either).