When buying a new piece of audio or audio/video gear, ask the manufacturer if it is AES48 compliant.
AES48-2005, ratified in March 2005, is the AES standard on interconnections--grounding and EMC practices--and shields of connectors in audio equipment containing active circuitry. The AES standard shows how to connect designated shield contacts to the shielding enclosure (chassis) through the lowest possible impedance path.
It provides a diagram of a star point connection (single point of reference) to equipment ground, the internal circuit reference, and the chassis, and indicates a designated shield contact on the enclosure.
The standard also describes how to deal with unshielded connectors, connectors built into microphone cases, and situations where the chassis doesn't provide a shielding enclosure (not encouraged).
While not part of the actual standard, the AES-48 document provides examples of what not to do and why, and how to fix existing problems. This is a document well worth reading not only for manufacturers, but for users of any equipment with audio inputs and outputs as well.
For more information on the AES48-2005 standard, visit the AES Web site.
