Help with Speaker Selection

My room is 20x20 with a ceiling that slopes from 8 feet on the sides to 16 feet in the center. The system is ARC 150.2, Naim CD 3.5, Sugden pre-amp and speakers Linn Keilidh.

One side of the room has 8 foot high shelving upon which the speakers sit. So speaker placement remains less than ideal.

I play rock and roll mostly. Any part of the system can be replaced but I have always enjoyed the ARC sound.

Will entertain any suggestion.

Thanks to all for their comments.
What don't you like about your speakers. Also what is your price range
They sound compressed, with poorly extended highs, colored midrange and minimal base.
Price range $2000 used
Vandersteens are always a good/reliable speaker, with good rock potential.
Inexpensive AND fun.

Get you a new pair of Cerwin Vega XLS-215's $1k shipped!
"One side of the room has 8 foot high shelving upon which the speakers sit.”

I’m not sure that I have an accurate picture in my mind, but the speaker setup, that I’m perceiving, looks like a bigger issue than the speakers themselves.
The older Linn's can sound pretty flat in the wrong set up and definitely is not a rock and roll speaker.

The placement is not clear to me, but assuming it's not behind the sofa or something, you might look at Spendor, Pro-ac or Harbeth. All have that great mid-range and top end, with manageable bass and will definitely liven things up.
Paradigm or PSB do rock well.
Thanks for the responses. Meriwan : you have summed up the sound perfectly with the word flat.
Phaelon: the room has a cathedral ceiling with a "wall unit" that's 8 feet high. Above the center of the wall unit the ceiling peaks at roughly 18 feet. The speakers need to be placed on top of this wall unit.
Mendota, that’s a very unique setup. At least it sounds challenging to me. I don’t have any actual experience with computer aided room analysis, but based on what I’ve read, your room sounds like a great candidate for it.
I don't think you need to waste 2K on speakers to place thusly. And I bet the poor sonics you are getting now have more to do with that placement scheme than the actual speakers themselves. Evaulate your issue before laying down your cash is my advice.