Such a newbie it's sick

Systems

Ok, still having the deck dilema. I'm trying to figure out which way to wire each to get the best performance. The Alpine CDA-7892 would be very easy to wire using a 4ch amp for the components and use the low pass filter built into the amp. A second 2ch amp with a highpass filter for the subs, and I'm done.

If I use the Pioneer DEH-P6400, I could use "Y" connections and again use a 4ch amp and a 2ch for the subs. If I hook it up this way won't I loose surround and dolby type features? Do they even exsist on car decks?

Another way I thought to connect the Pioneer was to use a 2ch amp for the subs and use the decks amp to power the components. I figure the decks 22x4 (RMS) watts would be plenty of juice for the GXR's I purchased. Especialy if I use low pass filters. Does anyone have any sites that show how to make 2nd order filters? I have a pair of GXR6's (front) and a pair of GXR69's (deck rear fill) What Htz should I cut the frequency at for these speakers?

And yet a third way to connect the Pioneer would to run the rear tray fill speakers off the deck with passive filters, Then buy a 4ch amp to run the fronts and the subs and use the amps crossover for them.

Yeah, so way newbie questions! I haven't a clue what would work best, and once I do that might help me make a better decision on what deck to use.

Thanks for any help or opinions.

Systems

After reading the Pioneer manual for the 5th time I just realized that I might not need passive filters for any of the speakers. Aparently it has a crossover (12db/oct low pass filter and a 18db/oct highpass filter for the subs) built in to the deck. Neat!

So, just gotta deside which of the three ways to wire it up still.