Every piece of the puzzle is important. All the components- speakers, subs, AVP, the speaker placements, room acoustics, and the setup (Levels, EQ, Room Correction, etc.).
We can take 2 identical systems, yet one system could sound amazing and the other one could sound poorly just because of the setup.
When I was using the Denon AVP-A1HDCI, I always raved about Audyssey DEQ, but with all my trim levels set at +5dB above standard levels. Because of this, my Master Volume was usually never above -30.0 and DEQ was very active. Also, I never noticed DEQ causing my surround speakers or any speaker to sound louder. The only thing I noticed was earth-shattering, heart-pounding, freight-train-from-hell kick-a$$ bass from my subs.
Just a note for people who use DEQ - changing trim levels will affect the magnitude of DEQ.