DP and 828, configuring DP and 828 Options

[MACSETUP]

Greetings,
My current setup:
G4 DP 800, OS 9.2.1, 1.25 GB RAM, 120 GB HD, DigitalPerformer 3.02, MOTU 828,
FastLane, USB iMic, several synths.
In my previous setup using a G3 400 with the built-in SoundManager I/O
and an analog mixer I could plug all the synths, etc., into the mixer and
then into the G3 via the mixers main outs. The sound out from the Mac was
input to a stereo pair in the mixer. This gave me the ability to hear all the
sequenced MIDI tracks on all the synths, plus any audio in DP, at the same
time. Choosing different MIDI tracks in DP would allow my keyboard controller
to trigger that synth, and it's audio output was audible, while still hearing
the other MIDI tracks playing back their respective synths. Except for not
being able to record seperate instruments to seperate audio tracks
simultaneously, this setup worked well.
For the life of me, I cannot get the 828 to approximate this flexibility
while adding the ability to do multitracking. Can this be done without a
mixer? If so, how? I have looked in both DP's and the 828 manuals for an
answer and so far no luck. I'm only able to hear one MIDI input at a time.
The various settings in SoundManager, the 828 control panel and DP itself add
up to confusion for me. Also complicating the issue is the iMic. Does it
figure in or not?
I realize this is a long question and probably asks for some basic
answers, but I would appreciate any info or pointers the group may have.

Thanks for your help!
Terry