ATC SCM40

vinylvalet we are a coda dealer and the coda does sound amazing with atc 

we have experience with adcom and vandersteen 

Dave and Troy

Audio Intellect nj

Atc dealers

If you plan on using the 10x9 room(system post) the ATC SCM 19v2 would be a better choice. I would also upgrade the amp/preamp.

As far as sensitivity goes, you do need a minimum of 120 watts for your amp and 150 is probably a better low end cut off. I drive mine with a Musical Fidelity A308 integrated and it seems to be a good match for my taste. Others would recommend something warmer. The consensus is that the active version is superior, but if you already have an amp and can swap for another amp, it’s a lot more expensive. 

I run the ATC SCM40 v2 passive using a SST Son of Ampzilla II amp with no issues. I think it’s a fabulous loudspeaker, made even more fantastic by the $2000 price drop. The use of the ATC-built tweeter made a vast improvement over the Scan Speak ferro-fluid tweeter used in the earlier SCM35, which was sensitive to amplifier choice (but I still drove it well with a 1975 GAS Amplifier).

This speaker, because of its sealed box design, is relatively impervious to major room issues and speaker placement. I get holographic sound with mine about 2 feet from the back wall. If you are worried about room loading, the smaller ATC speakers may be a better choice. I run ATC SCM7’s in my bedroom that sit on a dresser and work well. 
I want to emphasize that these are not hard to drive. I run the SCM7’s using an Adcom GFA535 II amp driven by a Schiit Saga (with a Sylvania 6SN7W tube) and the sound is glorious. The tweeters in this series are relatively forgiving. go for it! 

I would add that I think your amp would be ok with it. I would recommend a tube based preamp, mine work great with my Schiit Saga and Freya+, ARC SP6B, and my Cary SLP 05.