Aftermarket HU with a premium system?

I recently purchased a new car with the infinity premium 7 speaker system, and want to install my Alpine cda-9830 HU, but cannot figure out how to do it and I don't want to have to pay to rewire the whole system. Any ideas? Someone I spoke with suggested getting a PSI2, which I did, but still cannot figure out how to wire it.

Your interface box will have instructions for using it... Most of them will be pretty good, as well. If it is still over your head, I'd SERIOUSLY suggest spending the 50 bucks to have somebody install it. Please, this suggestion is not meant to offend in any way, but simply to save you all the time and additional money it'll cost you, if you were to mess something up.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

It does have instructions, but only shows 4 speakers and a factory amp, I have 7 speakers and a factory amp. The problem is this interface already cost us $35, and I really don't have another $50 to pay someone to wire it up. That is like $85, and for $75 I could have had the local audio store rewire the car without the interface.

The factory amp will drive all of the speakers, the deck and interface will not even see the speakers. I am not really familiar with the Infinity systems, OR the interface you mentioned, so I can't help with that exactly, but I expect you'd treat the interface as though it was being connected to the 4 speaker/1 amp system, and let the amplifier continue to do it's job just as it is now, with all crossover and other functions intact... I have a feeling, that any shop that says they can "rewire the car" without an interface, in a system like that, is probably a shop you might not want to deal with. I would expect that you would come back without a subwoofer, or something equally unthinkable like that. They might bypass the factory amp, and the system might not sound right anymore. The factory amps are LOADED with equalization curves for YOUR CAR, and without it, it won't (or might not) sound very good. The interface is manufactured for a reason, and it's more than to make 35 dollars of your hard earned. Really, I'd bite the bullet, and spend the fifty... It WILL be money well spent... and not good money after bad. I appreciate that you might not want to spend it, but think about how much money your time and frustration is worth. Probably more than the 10 extra dollars... and it'll be done right.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."