I am going to disagree with the above posters and say that you can get very excellent sound from Vandersteen 3A Signatures in a relatively small room. I have these speakers (without the subwoofers) in a 22 foot x 12 foot living room and I am very happy with the sound.
My system is set up the same way and I get excellent, balanced sound with good depth. The bass is not boomy, and I probably have mine set up closer to the wall behind them than you do. There are some challenges due to furniture configuration which I choose not to address, like a big wall unit between the speakers. This does cut down on reverberant sound and although I wouldn't call the sound "diffuse" at all, other speakers have given a more precise and more laser-like imaging presentation than the Vandy's in my room. They are not "slow" or dull or dark to my ears. I do lose some deep bass, from my room, as I live in a Manhattan concrete box and this does generate an amazing amount of bass energy into the next apt. rather than staying in mine, but you may not have this if the construction of your building differs from mine.
In spite of all the negatives of furniture in the room, speaker placement necessitated in front of a long wall, listening across the width of the room and thus barely sitting 8 feet away, with very careful setup, I was able to make these speakers sing. It was a lot of work and I was frustrated for months. Toe-in, tilt back and positioning changes of 1-2 inches can make a huge difference with these speakers. A very careful setup which relies on trial and error as well as sufficient time to evaluate different placement options can yield excellent results, if my experience means anything.
By the way, besides currently owning the 3A Signatures, I previously owned the original Von Schweikert VR-5 and have extensive auditioning experience with the VR-4JR, but not in my home. I do feel the VR-4JR is a better speaker than the VR-5, although they do share many characteristics. I owned the Vandies at the same time as the Von Schweikerts. Vandies unquestionably went deeper in the bass, although the Von Schweikerts were not a slouch there, particularly for their smaller size. Von Schweikerts had a more transparent midrange. The Vandies had a slightly more laid back presentation, throughout the mids and highs. The VR-5's were definitely more forward in their presentation. Although I liked the VR-5's overall, they were too big for my bedroom and I wasn't so in love with them that I would sell the Vandersteen's. I liked the Vandersteen's better overall. I am in love with the VR-4JR and am pondering trying to make that work someday as a bedroom speaker.
So, I wouldn't give up on the idea of 3A Signatures in a room even only 18 x 12, if the speakers are set up along the long wall as yours and mine are. This may not be ideal and we may be leaving some performance "on the table", but I am confident that my system sounds very good indeed with this setup. With careful placement, even with other room restrictions, excellent sound is possible and even readily attainable with work from these speakers. I wouldn't want a room any smaller than yours to work with and if my living situation changed where I had more room to play with, I would enjoy hearing these speakers in that environment.
My system is set up the same way and I get excellent, balanced sound with good depth. The bass is not boomy, and I probably have mine set up closer to the wall behind them than you do. There are some challenges due to furniture configuration which I choose not to address, like a big wall unit between the speakers. This does cut down on reverberant sound and although I wouldn't call the sound "diffuse" at all, other speakers have given a more precise and more laser-like imaging presentation than the Vandy's in my room. They are not "slow" or dull or dark to my ears. I do lose some deep bass, from my room, as I live in a Manhattan concrete box and this does generate an amazing amount of bass energy into the next apt. rather than staying in mine, but you may not have this if the construction of your building differs from mine.
In spite of all the negatives of furniture in the room, speaker placement necessitated in front of a long wall, listening across the width of the room and thus barely sitting 8 feet away, with very careful setup, I was able to make these speakers sing. It was a lot of work and I was frustrated for months. Toe-in, tilt back and positioning changes of 1-2 inches can make a huge difference with these speakers. A very careful setup which relies on trial and error as well as sufficient time to evaluate different placement options can yield excellent results, if my experience means anything.
By the way, besides currently owning the 3A Signatures, I previously owned the original Von Schweikert VR-5 and have extensive auditioning experience with the VR-4JR, but not in my home. I do feel the VR-4JR is a better speaker than the VR-5, although they do share many characteristics. I owned the Vandies at the same time as the Von Schweikerts. Vandies unquestionably went deeper in the bass, although the Von Schweikerts were not a slouch there, particularly for their smaller size. Von Schweikerts had a more transparent midrange. The Vandies had a slightly more laid back presentation, throughout the mids and highs. The VR-5's were definitely more forward in their presentation. Although I liked the VR-5's overall, they were too big for my bedroom and I wasn't so in love with them that I would sell the Vandersteen's. I liked the Vandersteen's better overall. I am in love with the VR-4JR and am pondering trying to make that work someday as a bedroom speaker.
So, I wouldn't give up on the idea of 3A Signatures in a room even only 18 x 12, if the speakers are set up along the long wall as yours and mine are. This may not be ideal and we may be leaving some performance "on the table", but I am confident that my system sounds very good indeed with this setup. With careful placement, even with other room restrictions, excellent sound is possible and even readily attainable with work from these speakers. I wouldn't want a room any smaller than yours to work with and if my living situation changed where I had more room to play with, I would enjoy hearing these speakers in that environment.