I'm designing a simple board with a differential ADC. The inputs are from TRS jacks that will (usually) carry balanced audio signals.
The datasheet, and general best practice, advises keeping analog and digital grounds separate. This makes sense to keep the digital ground currents away from the analog circuitry where they would contribute to noise.
I wonder then, where should I attach the screen from the TRS jacks? If these are balanced audio, the screen should contain only noise (RF and potentially ground loop hum) so it might make sense to dump it with the digital ground. On the other hand, it's not unusual for an unbalanced phono plug to get shoved in the jack, and now the screen is also the reference point for the signal so should be kept quiet.
What's best practice in this situation? And does the answer change if I'm certain if the equipment will only ever be used for balanced connections versus trying to design for either balanced or unbalanced cases?