I do a lot of multichannel listening and I’ve found no way to do so using iOS on an iPhone, which is limited to 2 channels. It would be normal that if you have 5.1 selected in Roon, but the endpoint, such as your phone, can handle only 2 channel, that Roon will downconvert to 2 channel to match the phone’s internal DAC.
Other than when I used to own an auto with a 5.1 DVD system in the vehicle — which enabled me to play DVD-Audio MCH discs in the car —, the closest to mobile MCH I’ve come up with is to use JRiver on a laptop PC, with a 2 channel USB DAC plugged in (I use the Dragonfly Cobalt) and emulating 5.1 sound using Redscape Audio’s PC-based software. No MAC version, hence no iPhone app.
Redscape (https://www.redscapeaudio.com/ ) has figured out how to delay the center and surround channels in a 2 channel wrap. The surround audio effect is really good on FLAC or DSD material, although decoding maxes out at 24/96.
At home, I use a small desktop PC bedside to power Roon playing out MCH through Redscape into a PreBox S2 Digital DAC, and then into a tube headphone amp and my HD650 headphones. It sounds like a full 5.1 system surrounding my ears. Give it a try, on a laptop or other Windows PC. JCR
No you can’t, it’s nothing to do with the apps it’s to do with the protocols used. If using a pc your using RAAt over HDMI which will support multichannel from a pc. When using network to Sonos.iys using Sonos streaming and that doesn’t support 5.1 nor does Airplay they only support 2.0 for audio only.