If you have 808.6 and SE speakers then it doesn’t look like you have an optimal setup.
If you have bought from a dealer, I suggest you go back and revisit the install.
If they have no clue, you either spend some time doing some Googling or probably live with a poorly setup system. Given the investment you have probably made already, I know what I’d do. But may involve some of your time to understand what you have bought.
It SHOULD sound amazing. Like I say, if you're using Roon, dunno why you have a chromecast.
Cheers
Greg