I have a 2000 C70 and bought a alpine IVA-W200 head unit and a alpine MRV-F345 4 ch amp. I went today to get them put in and was told that I needed to get 3 way crossovers to run them. They suggested getting the dynaudio but I looked into it and they are not cheap. I was wondering if the crossovers are necessary to run the system?

Are you using stock speakers or after markets? If stock, I dont know why the installer is saying you need X-Overs, if I remember right, what comes out of the stock head unit(HU-613, maybe the C70 stock units are different) is just Front Left/Right and Rear Left/Right. Also if the rear deck speakers are the same as mine are(S60) they are pre-wired 2-way speakers.

Unless you want to tweak the X-Over frequency between the woofers and tweeters you shouldnt need them, just keep the speakers wired the way Volvo had them and just use what would be the same cable that was there. That is what I'll be doing after I get the amp/sub box and cabling done.

If after markets, then you will probably need them.