"INPUT MON" stands for "Input Monitor" as found on "old" multitrack recorders.
(sometime called "Rehearse")

Also note that this is only relevant for Manual Punch.
When "Auto" (i.e. Auto Punch) is enabled, the DPS24 automatically switches
from Track playback to Input Source (on the Record enabled Tracks only)
between the In and Out point when it is in PLAY.
If the DPS24 is in RECORD Ready,
it will auto-punch into Record between IN and OUT.
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To make an assignment to the L/R, first call up the fader bank for the inputs.
Next, press the "Assign-L/R" button (above the Akai Logo).
As soon as you press any of the assign buttons, the inputs that are
already assigned to that will be lit steadily, the ones that aren't will be flashing.
To assign the input you're using to the L/R out just push it's select button so that
it stays lit and that's all there is to it (the same convention holds for assigning any
input or disc track to either the L/R or the group outs).
This is a good way to rehearse with tracks.
If you're getting ready to record, you can easily switch between monitoring
the input and the disc track using the "input monitor" button.
Just sending your input to the L/R out will let you hear it, but the level may
not be appropriate for recording...also, you won't have made any group assignment
necessary (unless you're using the "inputs direct" patch).

There's two ways to do this.
First, just push the "input monitor" button and you'll be listening to your
input instead of the track. The other way is just to have the track faders you're
going to record on up as well as the input up and both assigned to the L/R out.
Your input will sound louder (possibly an advantage when tracking so you can
hear yourself), but it will be a little "phased" sounding, since you'll be hearing your
input as well as the track simultaneously. When you playback, you'll only hear the track

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Rehearsal Mode:

1) when using manual record
* enable the INP MON key (Input Monitor) above the RECORD key.
This will switch the tracks that are armed for recording to input
monitoring, even during playback.
This way, you can also toggle quickly between track playback and input
to match your levels for punching into existing material.

2) when using auto-punch (AUTO enabled)
It's automatic:
* If you press PLAY, the monitoring will switch from track playback to input
monitor at the IN point and back to track playback at the OUT point (rehearse)
* If you press PLAY+REC, the DPS will go into record at
the IN point and back to playback at the OUT point.
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