I think of cables/interconnects as a more-or-less fixed cost, not as a percentage of the total system cost. Blue Jeans Cables sells Canare 4S11 speaker cables, terminated with locking bananas, for $5.90/foot. This might be 10% of a starter system, or less than 1% of your end game system.
If you think you can hear a difference between the Canare 4S11 and something many times more expensive, well, maybe you can. I suspect all you're really hearing is a difference in gain resulting from a change in length, gauge, or termination quality, Granted, a system may sound better (not just louder) at higher volumes. Usually, there's an app (or a knob) for that.