First, of all -- to ALL of you, a big THANK YOU! I really appreciate your taking the time to respond to my original posting. It means a lot, as I value all of the responses.
I see that I provided an inadequate description initially, so permit me to supplement it. My media room has already been treated -- the walls (with multiple acoustical panels), the floor (with acoustical padding under the carpet), and the ceiling (broken up into two heights). Since I use this room for watching movies as well as listening to music, the actual speaker configuration is 7.4 (no ceiling speakers). My side speakers are Revel Ultima Embraces, and my rear speakers are Arendal 1723 S THX. They are driven by a Krell FPB 200c amplifier and a Krell KAV-250a amplifier, respectively. Also, in the rear, I have two SVS 3000 Micro subwoofers just to help smooth the frequency response throughout the room from around 60 Hz down. My preamplifier/processor (for HDMI inputs) is a Theta Casablanca V. It is a truly fine preamplifier; there isn't anything else like it on the market (certainly not the ones made by McIntosh, Trinnov, Lyngdorf, Storm Audio, etc.).
Insofar as what I am trying to achieve, I look at this upgrade to "end game" audio system status as my "last hurrah" -- and then I am finished. I have to say, though, that looking at, listening to, considering purchase of, and ultimately buying audio equipment has been my favorite pastime for nearly five decades. Going forward, I suppose, I'll focus on how good (or poor) the recordings to which I listen sound. Already, I do like how the music I play sounds in my media room. What I would like to achieve is a little greater 3-dimensionality, a little greater accuracy in those faint sounds (such as a gently struck triangle at the back of the orchestra, better definition of singers in a massed chorus (e.g., Carmina Burana or Ode to Joy), etc. -- all while maintaining the wonderful musicality I now enjoy. I think that my source components and preamplifier send a signal to my amplifiers that contains all that I seek. Whether my current McIntosh amplifiers or my Revel Studio speakers are the reason that these "nth degrees" are missing, I have no idea. I do know, however, that for good reasons I am not about to change my amplifiers, and I am hoping that current state-of-the-art speakers (my Studios are now 21 years old) will provide the solution.
At present, the loudspeakers I am considering are the Rockport Avior IIs, the Magico S3 (2023 version), the Estellon XB Mk IIs, and the PS Audio FR30s. Thanks to the suggestions made in response to my posting, I need to add the JBL K2 S9900 and the Perlisten S7T Limited Edition. Unfortunately, in every case, determining which speakers I ultimately purchase will be an analytical exercise because I cannot listen to them first, ideally placed in my media room. In a very bizarre way though, I guess that is just part of the fun.
Please keep your thoughts and opinions coming. I really do welcome them.