ROKU Ultra 4802 compatibility with HDHomerun FLEX 4K and older Panasonic TV

Hi,

I have an Ultra 4660x2 that works great with a 10 year old Panasonic TV, all the apps work fine.  Then I bought a HDHomerun FLEX 4K.  The FLEX 4K gives no sound through the Roku but works fine on my PC and IPad.

From the little bit of info available on the web it sounds like the 4660 passes AC3 audio through which my TV can't decode.  I think my TV is looking for a PCM stereo input. Does that sound like a reasonable scenario? 

Here's the big question, will a Ultra 4802 fix this?

Thanks for the help.