ATC SCM40

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.

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 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!