most 850 with an external amp are the t5-r and r models. they sit under the passenger seat, or under the dash behind the head unit. even if u had it, u don't need to worry about it because u are getting a new head unit and amp...u can put in all ur own wires


i just installed an alpine amp with 6 infinity kappa speakers. used the 6-pin din rca for the amp connection (courtesy anthonyr on volvospeed). i still have a dilema for the front door speakers (have finished the rear pillar, rear door, and front dash). the wiring for the front door is not "threadable"...it is a completely sealed socket type and is a pain in the ass to remove. so i don't know whether to spend the time to put in an extra pin in the socket for my own wire, or the cut the stock speaker wire and tap it into my own wires from the speakers and amp.