I do agree with arremie even though i do not believe in investing expensive cables. A good build and quality cable is just fine to me even though its 'cheap'. I have 5 different cables now...

There are definitely differences in sound character but very subtle.System matching is the key as 'Arremie' said,but the problem is everyone hears differently and have different taste not to mention systems.
Those who do not find any sound differences in cables are the lucky ones! Might as well save the money and invest in better amps,speakers or sources...which i find is the logical route.

Another point is, why change cables to "adjust" the sound ? Many 'audiophiles' find it taboo to even touch the tone controls, when it is built for a purpose unless its a minimalist amp.

Just my view......

Humming does not necessarily comes from the sub only...check your interconnects as well, might be a poor connection or termination. Try separating the power cables from the connecting cables also.