Aftermarket Head Unit into 97 Volvo 850 wagon with premium sound system
 

I am currently about to put subwoofers into my 97 Volvo 850 wagon. It has a premium sound system in it. Is it possible to run the wires from the new amp straight to the stock head unit or is it necessary to buy a new head unit?

Also, I was thinking about buying a new head unit anyway. If I did this, would I have any issues with the new head unit communicating with the current amp in the car that is hooked up to the speakers? I was talking to the installer at Best Buy and he said that the stock amp could not communicate with a new head unit and therefore if I put a new head unit, I would have to replace all the speakers in the car. Is this the case? Any info helps.

Thanks.

You can bypass the factory amp. There SHOULD be a wiring kit out there for that. You don't have to replace the speakers. You should, but you don't have to. You could also replace the factory amp, with a new and better amp AND keep the factory headunit should you so desire. This isn't optimal, but would still be a pretty good step up from all factory parts.

So the aftermarket amp for the subs will hook up fine to the pre-existing head unit?
And if I did replace the head unit, the factory amp for the speakers would still be able to communicate with new head unit?

Just want to make sure I got this right.