LS430 2001 Stereo Problem

[Cepe]

Im helping a friend trying to fix his sound system in the car
it has a Pioneer standard cassette with 6 disc changer built in, with a mark levinson amplifier, also navigation.
He has had the car at Toyota garage and they tried another amplifier but same problem, when you turn the ignition on the speakers makes a "poff" and then you get no sound, tried navigation and when you change the volume you here the voice in the driver door speaker so it seems to work, also tried speaker by speaker back at the amplifier but get no sound from the stereo, took the stereo out and notice someone had connected a external mobile phone hub but had taken it out and left the cables there, the one that did it had cut 2 cables on the stereo connector, but he had solder em together again but it wasnt nicely done so i redid it, cutted em and soldered back up again, but now the stereo doesnt work at all, does the system needs some sort of reset when you take out the plug for the stereo?
and i have checked al the fuses btw

[drinkdrive]

when you turn the volume knob do you see the volume numbers change? mark levinson amps are notorious for failing.

[Cepe]

nope dont see volume change, tried to connect the outputs from the stereo to external amlpifer, i get sound then but nothing happens when i turn the volume knob, is that something with the amplifier then?

[drinkdrive]

most likely. when the volume wont change ive never seen a case when the amp wasnt bad. as for the shop that tested it with another amp...wrong model? who knows.

[Cepe]

yeah, tried to contatct em but the one that had been fiddeling with the car wasnt the so i sent away my friend, he was gonna check if they really had tried with another amp or if it was just a amp that was laying around that also could be broken, found a document on this site was indicated with product number it should be if it was an upprated one