I was always told that cables do not make a difference. 

Well here you have the proof that it makes a difference ,believe it or not and it can be measured scientifically in 2 different ways and also by the speakers output into the room when listening to music. 
 
You need the right software to find the problem.
 
The problem can not be detected with an oscilloscope when looking at the 50hz AC frequency of the mains supply.
 
It can only be detected when looking at the noise spectrum imbedded in a music signal.
 
All AV System solutions measurement shows that in a music signal measurement, 2/3 of a music signal is polluted with electromagnetic radiation noise and that comes out through the speakers into the room and affects the musicality content of the music being played
Cable design is frequency based and not current and voltage based
 
Inductance and resistance needs to be removed from conductors to be able to conduct ,without generating any electromagnetic radiation noise ,throughout an AV System solution
Inductance is creating phase and time shifting in conductors and diverting the noise just into a different spectrum of the same input signal, but it's not solving the inherent problem