m20j, I was on a similar search for over a year. My room size is 12 x 18' similar to yours. After thorough researching, and in some cases, also listening to several stand mount (bookshelf) speakers to integrate with my subs, I came to a choice that for me ( I emphasize for me) stood above all the rest. Keep in mind this essay is only my personal, subjective opinion and they all were great speakers that I was considering, but one in particular gave me the best presentation of the type of audio qualities that I was seeking. Here was my experience for what it's worth and hopefully it may give you some things to think about that may help in your journey to make the best choice for you. That choice may be totally different than mine or any else's on this forum. There is no right or wrong, best or better. Just differences and you need to learn what differences appeal most to you and fit your system. Everyone on this post is giving you very helpful guidance from their experiences. Be careful in how you put it all together though, including what I am writing about as well. In other words, take your time and do your research. Make your own kind of music (good title for a song, ha)!
I looked at Magico, Focal, Sonus Faber, KEF, SVS, B&W, several boutique brands, Klipsch, Paradigm and many more. The clear winner for me, and this was after reading everything about them and watching every video on YouTube multiple times, was the ATC SCM7, sealed box stand mount. I purchased my ATC SCM7 from TMR Audio and it was an exceptional experience with that vendor. Fortunately, on receipt of the speaker, my critical listening evaluations on all sorts of music (Innuos streamed and CD, Chord DAC), exceeded in satisfying all of the key audio qualities I was looking for which also corroborated the expert and user reviews. Music genre covered Rock, Jazz, Classical, Country, Heavy Metal, Alternative, Folk, Easy listening, Vocals and Instrumentals, old and new material)
The ATC SCM7, based on my subjective listening excelled in clarity (micro and macro details), impeccable mid range realism, crisp and clear, with very realistic musical tonality that was equal or better than the best speakers I was able to audition (again for my preferences). Vocals and instruments sounded just like they should. I never heard mid range like this from other speakers, even though my other speakers produce exceptional midrange. The SCM7 I simply unique and appealed to me. Others may be turned off and not desire such an analytical speaker. It's analytical but imo very musical, not clinical. It was realism to me. Sublime to me. It yielded very smooth beautiful highs that never were harsh, linear and with superb dynamics, the best center imaging I ever heard in my room with my electronics, a wide soundstage and overall excellent imaging. Many speakers out there can do the same or better. It didn't matter; I was hearing imo, for the first time, what midrange really sounds like. It just sounded more "real" is what I am trying to say. Most important these quality ATC drivers (specialty drivers hand made in England by ATC) gave me the engaging and often emotional and/or exciting experience I was looking for. I will explain later why they are not meant for everyone though; there are countless outstanding bookshelf speakers out there so I am just giving you what I experienced and suggest you do your own research on all speakers you are considering and include the ATC SCM7's. Someone else in this thread mentioned the ATC speakers sealed box benefits. Kudos for those comments. Know what you are looking for in the type of audio strengths you desire. Confirm that your electronics can drive these speakers ( a bit more on that later).
As I alluded to above, there are countless other stand mount (bookshelf) speakers out there that are truly excellent. I am not saying the ATC SCM7 is better than the rest. That would be nonsensical of me. They are not better than this or that, or are the best. They do something special so it depends on what the buyer is seeking. I am pointing out differences and you need to decide if they align with what you are looking for. To all reading this forum, your stand mount speakers are all "the best", for you and your room and system and preferences, if they are giving you what you enjoy in audio. I never view one speaker better than another; simply different and subjective to everyone's personal listening preferences. In my case here, the SCM7 worked for me and exceeded my expectations.
The ATC SCM7 is not a full range bookshelf speaker; nor is it warm, romantic or laid back. It is limited in bass (61hz); however, its's bass is tight, fast, and excellent. It does reach below 50 hz but is dropping off quickly in that zone. This didn't matter one bit to me; in fact it was one of my goals. I purposely didn't want bookshelf speakers with a port or extended bass; I wanted pure midrange and well presented highs. I wanted a sealed box. Try and find one. Magico makes one (10k), ATC makes them. I couldn't find others but there are likely some others out there. Nothing wrong with ports either; they are fine and can sound great! I own some and they are excellent.
The SCM7 is an acoustic suspension type of speaker. It has no ports which is also what I wanted for better integration with my sealed box musical subs. The SCM7 is a mid range marvel! For realism, precision, tonality; it exceeded anything I have ever experienced. That box was triple checked! The downside is they will reveal weaknesses in poor recordings and upstream electronics more-so than the majority of its peers; however, this is the quality of mid range I was seeking. And found it. If you want a forgiving speaker, look elsewhere. The speakers don't color anything and are precisely neutral from my personal experience. The SCM7 integrated seamlessly with my subs with the overall audio which totally exceeded my expectations sounding to me like what I would expect from $100k systems ( I have actually listened to such systems, Wilson, Magico). I am as pleased with my $1.7K SCM7's and B&W subs as much as having one of those high end speaker systems. I need money for groceries and utilities. No one else has to agree or disagree, and in fact can't really agree or disagree because they haven't heard my system.
Additional key factors- To experience what the SCM7 can deliver, it requires a high quality, high current amp with a decent sized power supply. Look at those factors vs watts. In terms of watts I would say at a minimum 100WPC (8 ohms). I am using a Coda CsiB integrated amp that is rated at 150/300 WPC 8/4 ohm (2 ohm stable), 130 amp maximum, 3000 volt power suppy, 80K uf capacitance. There are many amps that will work well and many that may be struggling to drive the ATC's (you don't want that). The SCM7 sensitivity is debatable (84db, however one reviewer measured 82). The sealed box is really a big plus imo and helps with sub integration. With a sub, these mid range powerhouses sound superb to me. You also need really good stands for the SCM7's and decent cables. Positioning, as always, is important and in my 12x18 room they are positioned from the tweeters, ~70" from the front wall, ~5ft apart, ~8ft to listening spot. There are also other variations that also worked well.
I hope this helps some. In summary, This entire long essay is not to commend or even recommend the ATC SCM7 to anyone. I believe the speaker is a good candidate for those looking for midrange accuracy and quality and detail; however, it is not for those who prefer the same qualities presented in a different manner. If you gain anything from this post, the key point is to make certain you know what type audio qualities you are seeking, know if your electronics are capable, and take time in the setup and break in period. These speakers will imo require subs as well. .
Enjoy your search and most of all take your time and research all your choices . There are so many great speakers to choose from that can be a great fit for your room, your gear, and most all your listening audio preferences.I have made far more mistakes over the past decades than good choices. It's not helped me so much in picking the so called "best" product but has helped me to more wisely define what I am looking for as well as better realize and incorporate the limitations that the room, the gear , our own hearing and discernment ability, and the recording quality itself play! Each of us have to find our own path. It's the only right one.