[intlplby]

how important is it to shield speaker wires and maybe put a "drain wire"?

 

[Pars]

Many aren't shielded (incl. commercial). At that point it is a pretty high level signal (much higher than an interconnect at the source level).

 

[SayNoToPistons]

Just keep them away from powercords and carpet/floors. Wrapping them with 2 layers of teflon tape should be enough.