After having some trouble finding an amp from a V70 I settled on a C70 4*100W amp (paid 50 euros with wiring harness and postage).
After discovering not many people had attempted this and most of them didn't document the process I decided to do it myself using common sense !
So first of all you need to get an amp from a C70 with the complete wiring harness.
Like this:
The others are the ones you have to wire to your speakers.
And there's the DIN cable to plug the amp into the headunit.
Next you need to identify the plug at the back of your radio that powers the speakers, it's the smallest of the two and the wires' colour should match those of your C70 harness.
That's the one:
You should keep the part with the plug if you want to remove the amp someday.
After that you're going to install the amp under the passenger seat like this:
You can ground the amp on one of the bolts attaching the seat to the body.
Next you need to remove the carpet at the feet of the passenger so that you can hide the cables between the center console and the carpet.
You can slide the wires under the seat rail and make them go into the dash just under the glovebox.
It should look like this:
You'll need to remove the trim under the steering wheel and find the passthrough to the engine bay.
It is located over the clutch pedal, to the left.
Remove the rubber gromet and shove both wires in.
Push the wires all the way in and then pull them from the engine bay.
You can try to sneak them to the right of the airbox and make them follow the thing around the cables going to the + terminal.
Feel free to ask me any questions and make suggestions !
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