Thanks.
In fact, I have written to Denis Morecroft of DNM and he has provided me with a helpful explanation:
"In brief, depending on the length (to some extent), the small diameter of the copper is an advantage.
The things you read about cable in the technical hi-fi press are generally wrong because the writers look only at the interface and they do not take into account the requirements of the amplifier and the problems that can be caused by overweight cables.
Excess/complex cable cross section causes magnetic distortion--ie the back emf is not identical in signal shape to the forward emf because the large amount of copper in the cross section which causes the formation of eddy currents. This is basic physics we were taught in our school days--the current in the cable induces and opposing current back into the cable. If the induced current is not collected evenly into the same cross section eddy currents will form. Multi stranded cables will definitely have this problem so stranding of the cable to increase flexibility is a no-no with audio cable.
An ultra-tight coupling between the speaker and the amplifier is not needed and it is even a disadvantage. For example most makers of high quality amplifiers use a resistance of 0.25 ohms in the line to improve low frequencies. The feedback system sees an ultra-low resistance cable as being more reactive than one with some distributed resistance.
In a nutshell these are the reasons why the cable needs to be just low enough in resistance for the task in hand.
If you need to use a very long run and the resistance goes up, then the decision is a balance between two factors.
1) is the passive effect of the slight variation in frequency response that may be inaudible
2) the active dynamic and magnetic errors caused by a low resistance cable and its interface with the feedback circuit of the amplifier which you can definitely hear."
