I have no experience with the ATC amps but have owned the SCM19's for the past 3-4 months - great speakers, and I much prefer them to my previous Harbeth m30.1's.
Initially I was using a single Benchmark AHB2 (100W/8ohms) - which drove the 19's very well. Later I got a second AHB2 and run them in bridged mono (380W/8ohms). This gave a nice boost in performance in terms of ease, dynamic freedom and perhaps soundstaging/imaging - though the overall sound was (not surprisingly) similar. It's possible some of the improvement came from having a dedicated amp/power supply for each channel and shorter speaker cable runs made possible with the mono arrangement. In any case there was a very worthwhile improvement in my setup with the amp upgrade.
I own a REL S3 sub which I mainly use for HT and briefly experimented with the 19's, but preferred the overall coherence without the sub. What surprises me about the 19's is the taut dynamic power and depth of bass available from such a compact speaker. No doubt the sealed cabinet and massively built SL spec bass/mid driver have something to do with this. I really don't feel any pressing need to employ a sub woofer.
Initially I was using a single Benchmark AHB2 (100W/8ohms) - which drove the 19's very well. Later I got a second AHB2 and run them in bridged mono (380W/8ohms). This gave a nice boost in performance in terms of ease, dynamic freedom and perhaps soundstaging/imaging - though the overall sound was (not surprisingly) similar. It's possible some of the improvement came from having a dedicated amp/power supply for each channel and shorter speaker cable runs made possible with the mono arrangement. In any case there was a very worthwhile improvement in my setup with the amp upgrade.
I own a REL S3 sub which I mainly use for HT and briefly experimented with the 19's, but preferred the overall coherence without the sub. What surprises me about the 19's is the taut dynamic power and depth of bass available from such a compact speaker. No doubt the sealed cabinet and massively built SL spec bass/mid driver have something to do with this. I really don't feel any pressing need to employ a sub woofer.