Dumb question

Just got my MPC 400 Plus and I can't get a sound out of it

Headphones plugged in, level knobs up, I see activity on the screen when
I hit a pad, "input" level meter registers. When I hit play, I see the
metronome start moving

Am I missing a step, like loading sounds first? Or am I missing an
outlet switch? Are there pre-loaded sounds in the unit?

Nothing I see in the manual or anything I've read online (and yes, I did try a search on this before I started a topic) seems to
point to anything except the most obvious and logical thing---that if you plug in the headphones you will hear sound.

The headphones work fine

What am I doing wrong or is the unit defective? I'd be relieved if
it's just me that's defective

OK, I've made a little progress--

I went into record and heard the metronome, so I know
the unit's amp is working

I saw in the pad assign pages that there are a bunch
of basic sounds loaded into the machine.

But I still don't hear the drum sounds in the headphones.
I see the meter react when I hit the pads, but no sound

Obviously, there is an assign out function or something
that I'm completely missing

I'll keep trying and consulting the manual, hopefully someone
will take pity on me and clue me in on the simple thing Im
not doing

you may need to change the "program" scroll down to it on the main page and turn the jog wheel.you will get a program menu.you then select the right program.

is the full level button on? It's to the left of the 16 pads.