As balanced audio do not touch ground at all, think of the „shield“ as shield only, which is not even necessary for differential signals (caried over twisted wires), but, if shielded balanced cables are used, that shield connects to chassis only and a (metallic) equipment chassis extends that shield to the electronics and connects input to output cable shields. In order not to introduce a ground loop, the shield connects only to the star ground at a single point (in the PSU chassis near the IEC inlet) and nowhere else.
In case multiple chassis are used, chassis and ground connectios are caried separately to the PSU chassis.