What is felt to be the best in wall speaker for a large den?

My wife is making me get rid of a pair of High end KEF book shelve speakers and said in wall would be ok. They’re paired with a 100+watt NAD surround system that I purchased from George Merrill’s Underground Sound 20 years ago. I looked at Bowers n Wilkins and Martin Logan so far. 
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Triad Gold or better. They don't sound like wall speakers. I use them for home theater and am definitely not sorry. You will need a sub of course but an in floor or wall sub will round out the package nicely. It will not be a high end audiophile system but you will enjoy it.
My view of in wall speakers is the same of that of Mr. Richard Vandersteen.  It has been reported that he said that when Steinway makes an in wall concert grand piano he will make an in wall speaker.