Hi this is my current setup with 75inch + Sonos Arc.
My question is whether this setup is fine or would this make the sound quality lower ?
As you can see I have a fire place and can't go any lower and making the TV go higher means it's too high. So would this cause any sound quality issues?
Also the upward firing speakers are definitely open and is not blocked - so is it still a problem ?
It looks like there is enough clearance for the two upward-firing drivers, so you should be fine.
thanks 
i am not getting the same effect that i got when i heard the demo at Best Buy - its not filling the room with the same sound effect - any idea why ?
Describe your room setup. How tall is your ceiling? Is it flat and without obstruction? How far are you seated from the Arc? What model TV do you have? Do you use any external media devices? Have you performed Trueplay tuning and adjusted the EQ settings in the Sonos app?
I am seated 13ft from the Arc. The ceiling is 9ft high and the room is 13ft wide.
It's a Samsung 75 Frame TV. And yes I have done true play tuning.
Will adding a Sub make a difference?
Adding the Sub always makes a difference, no matter the room size.
You can pick your Sub setup to match your room size from mini to full size or two full size.
A Sub will most definitely make a difference. It would also help if you sat closer to the Arc. 13 feet is too far to hear the height channel effects from the Arc’s upward-firing drivers. Try to move within 7-10 feet from the Arc. You also have a lot of hard surfaces in that room. Adding a rug or some softer surfaces will improve the acoustics of the room.
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