I'm upgrading the stereo system in my Crafter, put 2 new speakers in the front doors the other day now ive got no sound at all,,, seems strange, does the head unit know somehow they arent standard speakers??

Ive got 2 amps, rear 6x9's and a sub already mounted, just not wired up yet. Putting a new Sony head unit in this weekend to drive it all, is there anything i need to look out for in regards to power supply, ignition switching, radio aerial hook up etc from vw wiring to sony?

Ive done plenty of audio installs before, but this whole stereo not working now just from a front speaker upgrade plugged into the standard/existing wiring has me worried/confused....

cheers