I’m about to push the button to get 2 SVS 3000 micros to add to ATC SCM40s.

OP here. The subs arrived today and so far so good. I’ve been  fiddling  for an hour or two, but most of the adjustments don’t seem to make much difference one way or the other, other than the low crossover point and the volume.

My system definitely sounds fuller and richer, but I wish the lower bass notes were crisper and more well formed. Probably, I need to do more fiddling to get that, or perhaps it’s just the nature of my room and where I need to put the subs.

Anyway, there’s my report.

Subs do take time to break in, you may need to use bass traps to get the bass just the way you want:

Agree the subs likely need some time to loosen up and settle in.  

Try them in different positions around the room.

Thanks for reminding me about the break-in period. In my excitement over new gear, i forget several important things, such as this and turning off my Loki.

Unfortunately, there is absolutely nowhere for the subs to be besides where they are--peeking out from behind the mains. If I were single... maybe, maybe not. It's a weird, open space.