fuller sound at lower volumes


I am looking for a fuller, richer, and deeper sound at lower volumes. My current system is a Musical Fidelity a3.2 integrated, a3.2cd player, and Paradigm Studio 40 v.3 on stands. My room is about 18x12x8. I am thinking about a McIntosh MA6500 integrated. Or would adding a good subwoofer be of benefit?
valinar
A sub would be far more influential in getting a "fuller, richer, deeper sound" at lower volume than getting a new amp.
A good equalizer or an amplifier with loudness control.

look into the Fletcher munson curve