When choosing a UPS for use with your console, it should be of the pure sine wave variety, and have a output distortion of 1% or less. It is worth noting that many budget UPS designed for office use do not meet this requirement. 

When using a Allen & Heath system with a Surface and MixRack, or Mixer and Expander(s), these devices do not need to be fed from the same UPS. However, in all cases there should be no ground potential difference between any of the UPS's or the mains ground.

For components with multiple PSUs, it is recommended to connect only one PSU to the UPS, the other PSU should be connected directly to the Mains. In the event of a UPS failure your system will continue to function on the Mains power.

The 'transfer' time of the UPS from Line to Back-up power should be less than 2 cycles (20ms at 50hz, or 16ms at 60hz).