nonshielded magnet / speaker

Unlikely to matter - a permanent magnet is fixed like the earth's magnetic field it has no impact on ac signals. I doubt the voice coil will carry as far as that.

The speaker magnet could affect any inductors/coils making their performance non-linear and causing distortion. It depends on many specifics (such as what type on inductor, how it is oriented, how far from the magnet, how strong is the magnetic field from the speaker...etc.) as to how much of an effect.