The reason for using braided audio wire is that such wire is very flexible and therefore not at all prone to work hardening from being repositioned to curve around obstacles. House wiring can be solid because it is seldom repositioned, but audio wires may be repositioned many times. The latter is the reason that oxygen-free copper is often specified for solid wires: oxygen-free Cu is resistant to work hardening. That is, using solid wire creates the need to use oxygen-free Cu.