From
the manual:
The Hi / Low Z switch tells the UA5 what signal level to expect from the 1/4" inputs.
3. Input impedance select switch
Depending on the device connected to Input jack 2, use this switch to select either
high impedance (Hi-Z) or low impedance (Lo-Z). If you are connecting a guitar or
bass to Input jack 2, set this switch to the high impedance setting (Hi-Z).
The Digital / Analog switch controls whether the UA5 routes to its digital outputs an incoming digital signal via the rear coax/optical inputs, or analog inputs via the front XLR-1/4" and rear RCA rear inputs.
6. Recording source select switch
This selects the input jack that will be sent via USB to the computer as the recording
source.
DIGITAL->
The input of the Digital input connector (coaxial or optical) will be sent to the
computer. Use the Digital input selector select to select the jack that will be used
for digital input.
ANALOG->
The analog audio signals being input to Input jacks 1 and 2 and the Input jacks 3
and 4 will be sent to the computer. The audio signals from Input jacks 1 and 2 that
have passed through the Input sensitivity knob, together with the analog audio
signals from the Input jacks 3 and 4 that have passed through the Input jacks 3
and 4 adjustment volume, will be sent as audio data to the computer. For details
refer to the Block diagram (p. 14).
For recording with mics / matrix / SBD, set the Hi / Low Z to
Low, and the Analog / Digital recording source to
Analog.