What commerical audio system tweaks provide sound quality improvement??

Room treatment is huge! Hardwood floors are very reflective of sound. Area rugs are a great help, as you've discovered.
I have some windows to figure out. Too much resonance and ringing, but I hate curtains...

@jmccl12 those mirage speakers don't look too power hungry or difficult to drive, so I think you're probably fine with 14awg, but the only way to truly know is to try. 

The Best result from a tweak in my system was from Mana Acoustics stands for Naim SBL speakers! 
Dedicated 20amp powerline from the breaker to the System saves you the troubles of unplugging the fridge and all computers and light dimmers while listening. 
Shakti Stones, M'pingo dots, green markers and Black Holes for CDs, i tried them all: they make life Fun! ;-) 

@2channel8: You are definitely on the right track.  I'd add ear wax softener and a bulb syringe to your recommendation; used at regular intervals, maybe 5-6 times a year.  You'll be amazed at the improvement in your auditory prowess...

Vibrapods are excellent at isolation and vibration control and cheap too.

They all change the sound.....its up to the listener to determine if it's better or worse.