ATC users

I run ATC scm 19’s with a P1 pro in a nearfield setup. Any thoughts on which of these two upgrades. A: upgrade the amp to the P2 B: add a C1 subwoofer.?
the sub whould be nearfield as well, just in front of left speaker and about 4-5 ft from listening position.
I defer to tobes’ positive experiences above, however, the cost of 2 AHB2s + SCM19s is higher than a pair of fully active SCM19As and getting close to SCM40As, too, so wouldn’t think passive biamping is the ideal thing in comparison.
I agree with tobes assessment of AHB2 with ATC SCM 19 speakers. I am running the same combo and couldn't be happier. At one point I did get interested in trying out an amp with more power (I tried Parasound A21 and Cambridge 851W) but couldn't get the same tonal balance & accuracy as I am getting with my one AHB2 (stereo). This amp is only 100 watts, but due to its' 'no distortion' circuitry, all the wattage can be used. You need to listen to it to believe it. Whilst there is no need to add additional sub, I did try adding a sub-woofer to the combo, but since the tonal balance messed up badly (bass was out of control/sync in most of the tracks), I took it out.  I have listened to many hifi combos, but I keep coming to ATC + AHB2 for my needs.  All the best.
I am running the P2 with the 19s and in my smallish room there is no trouble getting punch out of the 19s. I have a C1 In the box and the CA2 preamp has sub out but I just did not feel I needed to even bother testing it.

only thing I would do over is just buy the 19As and bag the amp completely.