Is it that bad to run line level audio wires next to AC wires?

Question

I have to place my amplifier+turntable setup away from my working desk. Currently the amp has three devices plugged in: a turntable, a digital audio receiver and a simple jack output from my pc. Both speakers would remain on the desk, togheter with the receiver and the pc.

So I will need to run some wire between the new amp location and the desk. A total of 6 cables, two for the speakers, and two for each of the devices. The only acceptable way of connecting the two locations is running the wires in the wall, along an AC power line, for a total length of about 3 meters (10 ft). Moreover, the wall duct should large enough to fit the six cables (assuming 12 x 20AWG wires, or thinner).

I've came to know that, while everything unbalanced is sensitive to magnetic interference, and speaker signal is somewhat more robust, line level is particularly susceptible, and would suffer more from the AC interference.

Is there anything I can do to thwart the interference? Or will even the interference be a real problem? Could a coaxial cable be of use?

Below a terrible ASCII schematic, the wall segment begins at the sources and ends at the amp, inside the wall the wires would run along the AC power line.

                      WALL
SPEAKERS <------------------------------> AMP-OUT    All cables are ~10 ft.,
                      WALL                           all 10 ft. are in contact
SOURCE 1 <-RCA----------------------RCA-> AMP-IN 1   with AC power line
                      WALL
SOURCE 2 <-RCA----------------------RCA-> AMP-IN 2
                      wALL

Answer 1

Yes. Do not do this. You might get away with proximity if the signals were balanced, but with unbalanced audio, this is a bad idea. you are likely to get hum.

If running long distances, you might want to consider using balancing adapters to reduce rf and hum induction.