I’ve owned the SCM40s for 2 years, and I loved the sound of them. In my room, the ATCs imaged beautifully, were very musical, and never seemed ’stressed’. They handled everything with aplomb.
I have now moved to ATC SCM100A actives, and can confirm ATC’s assertion that actives are next level, sonically. They have the dynamic punch of planar magnetics, and the headroom to play loudly without fatigue.
Between the 19s and the 20s you mentioned, I’d say either would be a solid entry point into the ATC lineup. If you are on the west coast of Canada, there is a pair of 19A actives on Canuck for a reasonable price.
The other side benefit I’ve found moving to active speakers, is I was able to streamline my setup...and selling off my Benchmark AHB2, and the SCM40s, as well as speaker/interconnect cables, went a long way towards the step up in price to the active system.
There is a very good reason ATCs are in studios around the world. If you see the actual drivers themselves, as @soix mentioned, they are truly special.
Best, JAMES.

