The different cable theories I have encountered have mostly been covered above, but I think the following should complete the story.
1. Cables with shield connected at one end.
This is referred to as a floating shield design. The purpose of this design is to conduct any induced RFI/EMI away to a single grounded point.
Ideally, the end with the shield attached should be connected to the source of the signal - regardless of where that component is in the audio "chain" - e.g. for a Pre-amp to amp connection the end with the shield attached should be connected to the pre-amp.
This prevents any RFI/EMI noise from being communicated to the next piece of "amplification" in the audio chain - resulting in a quieter signal.
The problem with using these cables is - it relies on all of your components being correctly grounded.
However, components that use a two pin plug or a Wal-Wart power supply can experience grounding issues (i.e. because they are isolated) so for them, connecting the cables in the other direction may actually be more beneficial.
One such component I have actually had a measurable potential on the neutral side of the RCA output.
One way around this imperfect setup may be to ground the chassis/case of components using this kind of power supply design. This does not guarantee success - as it really depends on the component's design, but it's worked for my components
2. Conductor Extrusion effects.
When the wire is being extruded is has an effect on the crystalline structure of the material being used, which in turn MAY effect signal transmission in some way.
Whether you believe it or not, there are many cases reported on this forum of cables sounding different and there are several well documented reasoning's for this on the web, but one thing for certain, many cable manufacturers put little arrows on their cables in order for the user to get them both connected in the same direction.
One thing for sure - IF - there is some sort of rectification effect, you would want it to be applied in the same manner to both left and right channels, otherwise it would effect the phase of the signals between the two channels and degrade the sound.
So - it is advisable to connect both cables in the same direction - hence the little arrows, but which direction may well be system dependent
3. Cable architectures
There are some very complex cable architectures out there now and connecting such cables one way or the other may have any effect on sound.
However - you DO want to have both cables connected in the same direction - hence the little arrows.
A cable architecture can be responsible for a noticeable degradation or improvement of sound - depending on which way round they are connected and in general the manufacturer gets the little arrows right, but there is no harm in trying them the other way around - just to see :-)
So, to sum up - in some cases the little arrows may only be there to ensure you get both cables connected in the same direction because the manufacturer believes it to be important. The actual direction BOTH cables must be connected in may be system dependent.
If a cable uses the floating shield design then it should be stated somewhere in the manufacturers literature, together with the "direction" the arrows should be connected.
One company I know uses this method is Van den Hul and they document it quite well.
Of course, there are those that believe a company will add little arrows on their higher end products just as a selling feature - just sayin :-)
Regards...
