Shielded mains cable

I have just be evaluating a German built tube amp
(4 pairs of EL34 in push pull parallel) It was supplied
with a mains cable, which in addition to the L, N and
Earth wires, had an external woven copper plaid
screen/shield, under the clear plastic outer cover.

This shield appears to be connected to ground at
the amp end only.

I have seen something similar in studio/broadcast
control room racks, where test equipment was built
in, and powered from an AC outlet within the same rack.
The mains leads had a screen to prevent the possibility
of AF signals affecting measurements.

But what about in the case of audio equipment
built for use in the domestic environment?
Any opinions?

Regards to all
Iain



.