Hey, i just bought an Alpine CDE-122 deck. Heard it is a very good system but its a 4 channel. I have 6 speakers so im guessing i have a 6 channel system? The guy at Car Toys told me that if i just bought the wiring harness and plugged it in it would only play out of the 4 speakers, but i want all 6 speakers to work. What should i do? im trying to avoiding rewiring my whole dash like he said. My car is a 1994 E320. How should i go on about doing this?

Thanks