I agree, the room is the most important component. But after that, the speakers. B&W (and KEF) are known for their tonal balance and imaging, not so much their dynamics - Pace Rhythm and Timing (PRaT, as the Brits call it) and slam, certainly not the way Klipsch and some other brands like JBL are. These are subjective qualities yet instantly identifiable when heard. Maybe some kind of dynamic compression. Finding a speaker that combines dynamics, imaging and tonality can be tough.
After that, the ability of the amp to handle the impedance (deliver current) and control the drivers especially their back EMF is a key part of amp-speaker matching. Back in the 'receiver wars' era the 100w/Ch and up mainstream receivers all sounded horrible with demanding loads, like Double Advents, or big JBLs and Altecs due to budget-compromised power supplies and heavy current limiting that allowed admirable numbers on the bench, but poor performance with demanding speaker loads. To a lesser extent it still happens today, as amp designs have improved. But it remains - some otherwise excellent amp designs presuppose certain speaker behaviors, and just don't sound 'right' with others.
Beyond those items, the rest is all front end and source, a whole ' nother set of topics.