Hello, Fivestrings.
I owned an IDA-8 for approximately 5 years. I say 'owned' because I handed it down to my son for his starter/house warming audio system this past November. [Yes. I miss it. However, I now own an IDA-16.]
The ATC SCM7 v3 speakers are similar enough to my pair of Fritz Loudspeakers LS/5-R speakers that I'm pretty confident I can offer useful advice. The SCM7s are rated 84dB, 8 Ohm while my LS/5-R speakers are 83.5dB, 8 Ohm. I drove the LS/5-R speakers with the IDA-8 only to discover that the amp just didn't have enough power to make the speakers 'sing'. Sure, they made music together, but there was a lack of dynamics. [Somewhere in this circle, I've written about this before - likely 4+ years ago??] Anyway, I was not satisfied with the IDA-8/LS/5-R combination, and tried other amplifiers searching for a better pairing.
I tried the ST-10, a Taiwan made tube amp, and an IceEdge 1200as2 amplifier over the course of 3(?) years. I feel the IceEdge amp does a very good job of making the speakers 'sing'. It's not as warm sounding as the IDA-8, but I can modify my system by choosing a warmer sounding DAC (for instance) to tweak the sound. The tube amp sounded great, but it was just too expensive to seriously consider.
Over the years, I tried several speakers with my IDA-8 and discovered that two-way monitors with 87dB (and higher) efficiency tend to sound pretty good. However, bigger, floor standing speakers - even those that are high efficiency - tend to sound a bit thin, and lack dynamics.
I really enjoyed my time with my IDA-8. It's a really cool little package for how much it costs. My sole complaint over the years was that it would be even better if it were 150 to 200 watts/channel. Of course, if the IDA-8 had 200w/ch, there would be little or no need for the IDA-16 to exist.
You haven't mentioned your room size. If you plan to listen in a small room, an IDA-8 may be enough for your needs. If you want dynamics and want your speakers to 'sing', you may wish to explore a more powerful amplifier. YMMV, of course.
Kudos to Jason's engineers for creating such a great little amplifier.
Regards,
Michael