Hi
@Love4sound, I am using
SONUS 3540 as heights for my Atmos setup. It sounds great and I get 85% Atmos experience from mine (You get 100% realistic effect in the ceiling mount). SONUS 3540 has a sensitivity level of 85 dB & impedance is 8 Ohms, but as yours is 2400 receiver, it will drive 3540 effortlessly. It has a key hole slot and I wall mounted using the same. It comes with wall mount bracket installable from the sides.
I am not sure about the Sonodyne showroom in Chennai for audition but Polk OWM3, you could go to ProFX.
@RajithKumar - Please share your experience from your installation