Have you checked the 'digital +9vdc supply'?
It should be pretty free of any ripple voltage (Vac).

I would build a tried & true amplifier.
Attached is a simple low power amplifier.
Tube Works TD 742.
Build it.
Study it.
Blow it up.  :lmao:

A TA-7200 P 10 watt power amplifier is used to drive the reverb pan.
It appears to be a 1.1 Vac output signal on the schematic.
Measure it and see what you have.

ICE Power schematics have never been released as far as I know.

I have attached the input circuit diagram.
The signal branches off of IC2A to the Clean and the Crunch channel.
Either of those is selected by jfets. (Clean/ Fet1: Crunch/ Fet2)
You will need to track down where in the Clean circuit the signal is failing.

" switchmode amplifier, PWM (pulse width modulated) amplifier and Class-D amplifier"

!!!"  DISCONNECT any speaker"!!!

Try the guitar into the Zoom & then go into the FX Return jack.
This will tell if it is a Send circuit issue or a Return circuit issue.
Be aware that you may have to adjust the gain on some of the Zoom presets.

To answer the posts question, here is a crop of the power amp board locating D16 (+16Vdc) and D17 (-16Vdc)

Piease post the relevant schematic.
You really should test the power supply before assuming the failure mode is the exact same.

http://www.rru.com/~meo/Guitar/Amps/Lab/schem.html

-7Vdc on the speaker out connection indicates a failed output section.
The lower minus part is turned on when it should not be.
Do not hook up the speaker until this is resolved.

You will have to remove the old solder from the PCB before you install the new jack.
You will need a solder sucker,
Or 'solder braid'.

Here is the schematic.

Nope.
Pretty rare pedal.
They only made about 100 or so.