I have to questions about the Ultra. First, can I source a USB to AC power cord instead of using the included wall plug? I am short on outlets but have a USB port nearby to use as power if it will work. Second, does it support Dolby Atmos? I have Netflix 4k account and Vudu UHD titles with HDR and Atmos and I am hoping to use the ceiling speakers.
USB ports only supply 5 VDC, while all Roku players other than the sticks take 12 volts. So a USB port doesn't have the voltage required. . Your Roku Ultra does support Atmos on Vudu. I haven't checked lately, but Netflix had an exclusive deal with LG and Microsoft for Atmos support, so other brands of streamers won't support it. But remember that the Atmos offered by the streaming services is not the same Atmos available via a Blu Ray disc. The disc has Dolby TrueHD, which is a lossless audio codec. The online sources offer Atmos via Dolby Digital +, which is a lossy codec. But hey, it's still Atmos.
Dan Roku Stick (3600), Ultra (4640), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.