The room is a much a part of the system as other components, yet largely unrecognised or ignored by most people, despite the fact that it may have far greater influence on the sound than cables and ethernet switches etc, e.g. often having a major influence on clarity and on both boominess and missing frequencies. Getting the room right can completely transform the sound, though of course the degree of affect in any given setup depends on the room itself - shape, dimensions, construction, surfaces, furnishings - and on any imposed or chosen limitations on speaker and listener placement, and on how full a frequency range is the music played.
Assessing the room is a key part of determining treatment, and for that purpose a tool such as REW is invaluable: It is free software (full name Room Equalisation Wizard), though it needs a neasurinv microphone - the one they recommend is good, though I think it costs around £100 new. With it you can see (literally) what is happening in the room: resonances, excessive reverberation etc, even, for an experienced person, how much early reflections are having an effect.
Also as Suedkiez observed, some suppliers such as GIK offer a free service to assess what treatment would best suit: