Help with Audio formats and home theater

[SANAFABICH]

Hello everybody! Thanks in advance for any help provided.

I'm planning on buying a new AIO home theater since the one I have is a little dated (I've had it for almost 15 years now), since it doesn't support Dolby Digital Plus. I pinpointed this lack of support as the culprit for all the noise, cracks, pops and loss of audio signal when watching 5.1 content on netflix and Prime Video. Blu Rays are OK, but I think Netflix and Prime Video use some sort of dolby digital plus / dolby atmos hybrid that causes this problem.

Anyway, I tracked down a AOI home theater that supports Dolby Digital Plus, The Sony BDV-E2100. I'm currently watching Netflix via the Roku Stick, and have an optical cable connecting the TV with the home theater. And this is where I need assistance: The manual for the Sony Home Theater states that Dolby Digital Plus is not supported if I use the optical audio in:



Is that really so? Does this mean I will hear no audio at all, or the same noise and static I hear with my current home theater?
Is it a limitation of the optical audio? All DTS formats seem to be supported via optical cable. What gives?

As far as I know the only way I can get the 5.1 signal from the Roku Stick is using the TV's optical output. I've heard about HDMI ARC but I have no idea how it works. Both my TV and the Sony Home Theater support HDMI ARC if that helps.

Please help!