Is that a two-channel amp? Which model?
Volvo frequently used solid color and striped for speaker pairs; you might want to clean off the wires really welland look in a good light to see if, e.g., what you show as a wire with a black stripe is really a dirty one with a brown stripe.
The connector positions on the wires didn't change much among the radios and amps with the same types of connectors--can you post photos of the wirng connectors and the back of the radio? I'm assuming that you have the 9-pin radio connector from the year of the car. Wiring colors changed somewhat, but the connectors would stay the same for several years, so they could sell upgrades--if I'm guessing right on your radio, the connectors were the same up until mid-88 or so, then there was a change which lasted through most of the years of CR- radios, and two more since then.
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We have met the enemy and they is us. [Pogo] S70 cop car : Rough Rider tires& suspension, Walmart fog lights, eBay speakers, ambiance by Pall Mall, trim by Le Duc d'Tape, 8-channel THD by OEM amps