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

Congrats OP! I use two SVS SB-4000 in my room, and I influenced a friend to get a pair of the SB-3000 micro. He has a smaller room than mine, and he’s quite happy with them. My favorite feature is the ability to tweak phase by degree from the mobile app in my listening chair (or any of the other settings as well). The app experience makes it a delight to tweak and further integrate the units into the room. 

@m669326 I usually adjust one sub at a time. And yes, be patient with break in  

How big is your room?

I would say that if you also want optimal performance, good quality power cables and subwoofer interconnects can make a profound difference in the speed and definition of the bass. 

@m669326 Did you buy your SVS Micros new? Had your room size been mentioned or if guidance was sought on the appropriate subwoofer for the room, I would have advised to go with SVS’ larger offerings. The 3000 Micro have good specs for their size, but they are intended for use in small and medium sized rooms at best. With a larger room, especially with vaulted ceilings which add to the cubic volume, it will require more out of subs to charge the room. My room is 18x23 with a slanted ceiling up to 18’ high. It is also open to another room adjacent. I owned a pair of the SB-3000 (not micro) and they could not perform with authority. I returned them in a week’s time and upgraded to the SB-4000. What a huge difference. Just some food for thought if you bought direct from SVS. At least their return and exchange policy are exceptional.