The outputs are balanced, transformer-isolated (phantom power tolerant) and low impedance (~50 ohms), designed to interface with standard microphone preamps. They require 40-50 dB of gain for a decent return level. (As a point of reference, on a Mackie or Mackie-clone mixer, a gain setting of 3 o'clock works well.)
The output grounds (pin 1) are completely isolated from the input and from each other. Logically, this arrangement is like a reverb chamber; the outputs can be thought of as coming from a pair of microphones inside the box. There is no possibility of ground loops.