several years ago I had purchased a Roku Ultra for my Summing TV. the unit works great but the sound it's good from the TV speakers. I then purchased a Roku Streambar speaker system. After failing to get the system to work properly and several communications with support I was told that "You can NOT use two Roku systems on one TV" so my options are disconnect the Roku Ultra and listen to great sound on the streambar or disconnect the Roku soundbar and listen to the weak speaker on the TV, why doesn't Roku state online or in the Quick Start guide that "You can NOT use the two Roku products on the same TV? Now I have a used system that I can't use.
I have 2 Ultras on my samsung, one on hdmi1, the other on hdmi2, the audio playing thru my AVR via the TV optical output. TV hdmi2 is eARC capable, but I disabled that function in the TV.
Do you have an optical audio out on the TV to connect to the streambar? If you do, try using that and disabling ARC on the TV, if that hasn't worked for you.
I don't have a streambar, so I can't verify that will work, though.
@tinman, I don't know where you heard that you can't use two Roku devices on one TV, but if you heard it from Roku support it often seems that they'll say anything to get rid of you. I have a stick and a Streambar connected to the same TV and I get sound through the Streambar for both devices. I have no doubt that I could replace the stick with an Ultra and it would work just the same. The Streambar is connected to the TV's eARC HDMI port and the stick is connected to another HDMI input. There's not really a good reason to use two Roku devices in my case. Why do you think you need both?