Alesis QuadraSynth Plus Reference Manual page 143

Editing Effects: Chapter 7
which Pitch type is selected. If the signal is taken from the effect
send, the Reverb will receive direct, uneffected signal.
Input Balance
Quad Knob [3] allows you to control the balance between Reverb
Inputs 1 and 2 and therefore control the blend between the
various input sources. This makes it possible to have the signal
from the Pitch or Delay sections, or the direct effect send in any
combination or amount.
QuadraSynth Plus Piano Reference Manual 144