Perfect match for ATC speakers

Have a look at Van Alstine. They may have what you need. Few months ago I bought a used Synergy 450 (225 wpc @ 8 ohms) directly from the AVA website to use with my EgglestonWorks Fontaine Signatures (legacy now per EW website) and am enjoying it greatly. It has transformed my listening volume to a lower level because it’s all there - dynamics, detail, space between instruments, full and robust. 

+1 active ATC.  Just do it and never look back.  Roll past the pedantic active vs passive dialogue.   ATC 19A will crush the ATC 11 (a very good transducer in its own right) and any power you will pair them with.  At least seek out a pair of active ATCs and listen.

But they do need something>120w @ 8ohm because they are measured at only 82db efficiency.

George, once again a pile of uninformed BS. Please stick to what you know( (as opposed to what you think you know) I own a pair of ATC SCM11s which I am listening to right now powered by a pair of these:

https://www.theabsolutesound.com/articles/exposure-3010s2-mono-power-amplifier

Steroephile Editor’s choice recommendation - they are a dream team made in heaven and can absolutely rock it it out if need be: nb see Martin Colloms measurements.esp into low impedance loads. You can look them up, I am too tired to bother.

t‘s all a about quality, rather than quantity.

I've never heard an ATC/Exposure combination but I've heard nothing but praise from others.

BTW, this thread is a perfect example of why I steer folks away from the forums. The odds are very high that you'll end up acting on really bad misinformation; typical of the internet in general. In this case from folks that haven't heard the speakers, have only heard an ancient model (ATC has been around since 1974), have heard a pair in less than optimum conditions or folks recommending amplifiers that they haven't tried with ATC speakers.

With that said, I have heard multiple ATC/amp combinations. Your best bet, as mentioned by several experienced posters above, would be the ATC P1 amplifier (retail $3749). The CDA2mk11/P1/SCM40 combo won best of show at the 2019 AZ Audio Video Club speaker fest against some stiff, in most cases much more expensive competition.

For greatest value and a very simple, clean system choose the ATC SIA2-100 integrated (retail $3999) with similar but lower power than the P1 and excellent built-in DAC. This is a very popular paring with the SCM11. Connect a quality streamer like the Roon Nucleus, subscribe to Qobuz and Bob's your uncle. I've heard this combo with both the SCM11 and SCM19 passives; outstanding in each case.

I also agree with a poster that the ultimate ATC experience is with their active models. But we just mention that as an aside since you already have purchased the excellent SCM11 speakers.

You have an outstanding, for life speaker. Continue to use your ears and don't let anyone else tell you otherwise.