Mario,
the signal wiring passes in close proximity to both the power transformer and the power filtering choke.
Having already experienced the effects of induced signal in external cables I rather think the shielding to be important.
I could be wrong, would not be the first time
Having noted the apparent loss of weight and body with my experimental Cat 5 I/C, I would expect a similar effect, perhaps incorrectly so, with using Cat 5 for this application.
I was looking for some indication of the possible effect, "sound" if you will, of using either thicker or thinner, stranded or solid wire for this purpose.
On received advice which is currently working well in other areas, pure copper, unplated, is my thought.
Perhaps twisting is a solution to possible noise pickup, that is something of which I am also unsure, the possibility of adding a third wire, unconnected at input to make a twisted triplet with the third wire being a "drain" also occurs to me.
Comments ?
