I believe the key to hiding the cables is getting a cable management system that allows you to plug the Arc into a power socket behind the TV or behind your media console, not behind the Arc. See this video:

Thanks Superstar.  If I get inspired I may try moving the socket.  In the meantime I think I’m going to look for some sort of cap or covering to discreetly hide my mistake!

It looks like your Arc is mounted upside down.  Obviously, that matters with an Arc since your upfiring speakers are now down firing.  Mounting it right side up may help hide the wires a bit. I’m not aware of anything that could cover up the existing place you’ve already got though, if the Arc can’t cover it up by itself.

My Arc is sitting on a fireplace mantel, and I actually haven’t bothered covering up the HDMI and power cable at all.  It doesn’t bother me much.  I could do the easy way and put it in a track to hide it, which I’ve done in a different room.  I don’t think I want to cut the wall as I just don’t think I’ll be able to hide it entirely, nor will it look that much better than exposed cables.

@GuitarSuperstar, it’s often not within building codes to have high voltage power cords behind your walls unless the cord is specifically rated for in wall use.  To my knowledge, the Sonos power cord isn’t rated for in wall use.  There are kits that include power cords that can be used behind walls, and I assume the ones Sonos sells will be properly hidden...but I haven’t looked into it.

I’d add that not only are the upward firing speakers firing down, but left and right would be reversed :)

You can fix that by hanging the TV upside down as well though.  I don’t think their is a solution for the vertical reversal though, as helicopters should never come from the ground. 

Hi melvimbe.  If you look at the pic i posted the SONOS name is right side up so I believe it’s hung correctly and  the sound is great. the echogear wall system i used is rated safely for behind wall usage so no problems there.  just need to figure out a cap or cover that’s aesthetically pleasing at this point i believe.  thanks.

Look at the pictures at 

https://www.sonos.com/en-us/shop/arc.html?

You’ll note that the “notch” where your cables are is supposed to be pointing down, and the “top” of the Arc is supposed to be uniform across the length. 

@ydbp The word “SONOS” is a palindrome, so it reads correctly right side up and upside down.

The word ‘SONOS’ is a palindrome, where it looks the same forwards/backwards...upside down.  Like RADAR, TENET, TACOCAT.  Besides the notch @Airgetlam was referring to, you’ll also notice that the speaker grille (where the audio comes out) is pointing out and down, rather than out and up. The feet of the ARC should also be on the bottom, rather than on top.  Trust us, it’s mounted upside down.

OMG you’re right Airgetlam!  It didn’t occur to me that SONOS looks the same upside down as well as right side up!  I just flipped it right side up and it’s perfect!  Thanks to all of you guys for your help.  God bless the interwebs.

I think GuitarSuperstar and melvimbe deserve a lot of the credit, honestly. I just helped.