I was wondering would these work?
Wall Bracket for Q150 & Q350 The B2 wall bracket allows you to easily mount the Q Series bookshelf speakers for even better integration into your home environment. ENQUIRY WHERE TO BUY
us.kef.com
My opinion is that I wouldn't mount a speaker directly on a wall. I'd set it several inches off the wall, and probably aim it at an angle from the surface plane of the wall.Otherwise, you can get really wonky cancellations in the midrange.
Put your speakers directly on the wall surface, holding them up with anything you care to sue, and see whether you like the sound or not.
What mystifies me is that 20 years ago, there were adjustable speaker mounts on the market that clamped the speaker and held it securely that way. Try as I might, I can't find any of them for ceiling mounts any more.
Jim