Hi @naomi143
Welcome to the Sonos Community!
I think you would have to locate the Arc so high that you would be unable to discern the difference between the height channels and the normal channels - they’d all be above you.
Additionally, I can’t see how the ledge would make any difference - it’s too close to the wall, and has no horizontal surface for sound waves to reflect from.
I’m sure the Arc could serve you well in this room, but not if Atmos rendering is important to you.
I hope this helps.
Thanks Corry,
Honestly, Dolby isn’t an important factor since I know my living room isn’t set up for it. I have looked at the Ray w/ surround sound speakers as well but I wasn’t sure what the sound quality difference would be between the two. I may just go ahead and pull the trigger on the Arc since my husband and I are planning on moving in a few years. Who knows…. Maybe the next house will have lower ceilings 
Actually, since I brought that up….. if I move and bring the Arc with me, will I still need an amp if I have the house setup with architectural speakers?
Renee
Hi @naomi143
I think it’s safe to say you will get a considerably better sound from the Arc than from the Ray - both the size of the unit and the number of speakers goes up considerably with the Arc.
If you plan on using Architectural speakers as surrounds for your Arc, then yes, you’ll need an Amp too.
I hope this helps.