Speakers least affected by room acoustics

There are frameless paintable acoustic panels out there that can be adhered flat to the wall surface. They blend in pretty good. And in your case, put high up above normal sightline / above normal decor and wall art, high up in the corners will help with echo... I’m searching for these again myself. I know there out there... 

@recordchanger2018 The guy who designed the Emerald speakers moved on and founded Spatial Audio, which is his current company.  Check them out over on Audio Circle.

Another for " headphones ". Also, I agree with willemj, although I believe it is with all frequencies.

If the main concern is sound reflecting off the ceiling, then either dampen it with some form of acoustic treatment, or get a loudspeaker that is specially designed to reduce vertical dispersion.   Consider something like this:

http://www.daytonaudio.com/index.php/epique-cbt24-line-array-speaker-system-pair.html

There are plenty of alternatives.  Do some research on line array loudspeakers.

Headphones are not vulnerable to acoustic waves but they are vulnerable to RF interference. The headphones per se and the cables and the electronics.