I believe you are perceiving a difference. Many do. I can't hear a difference between my $200 monster cable (free - thanks to Julian at Visions) and $20 twelve gauge. At least one very competent designer in the audio industry claims anyone can hear differences between any kind of cable in his "lab".

Can you describe the differences you're perceiving?

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated