front, rear hu signal difference?

My stuff: HU: Pioneer DEH-P980BT X-over options: Auto/Manual TA and EQ capabilities of: Front and Rear out:    High Pass Only XO points 50-63-80-100-125-160-200Hz    Slope -12 or -6dB/oct. Sub out:    Low Pass Only XO points 50-63-80-100-125-160-200Hz    Slope -18, -12 or -6dB/oct. AMPs: Eclipse XA4200 100W rms 4ohms/200W rms 2ohms       X-over For both Front and Rear Ch. inputs: HP or LP 40-500Hz       Eclipse XA1200 300W rms 4ohms/500W rms 2ohms       X-over: LP 45-200Hz Speakers: Two pairs of PPI 355cs's with passive XO's (can't find info on XO)           Mid-bass drivers yet to be decided           Sub yet to be decided leaning to Eclipse SW6210 or something someone recommends that will be good for loud LOW bass between 20-50Hz Is there a difference in the signal being output through the front and rear channels of a HU or is it just a duplicate set of L&R? (not concerning the fact that you can change X-overs, eq, etc.) Here is my plan... NOW: 1) Put the one pair of 355's up front with the woofers in the stock door locations. 2) Put the other pair in read doors (for now) Later: 1) Get rid of rear DOOR speakers 2) Get 6.5" mid-bass drivers for ~ $100 pair (tang band W6-1139SI OR... Suggestions please)and put them in my rear DECK and use the rear channel to feed them and maybe make some X-overs for them OR...    QUESTION: Could I use the Rear channel High pass filter in my HU at 50 or 63Hz @ -12dB/oct. and the Low pass filter on my XA4200 at say 200Hz to kind of "make" a crossover for the mid-bass drivers? I would then use my HU's Front HP filter at 200Hz and its sub LP at 50 or 63Hz @ -18dB/oct. MUCH LATER: 1) Move mid-bass drivers to front doors and make custom door panels for them like concept in pic below with 355 on top of mid-bass.    QUESTION: Will moving the mid-bass drivers that are getting the rear out signal from the HU be bad in some way and so I should just Y-cable the front outs to all four inputs on my amp? But if I Y-cable the front outs then I have to make X-overs for the mid-bass's? Will this screw with the Auto TA calibration(Manual TA operation available also, just think Auto TA is more accurate)?

Here is the pic. I don't know Why it didn't work.

NO opinions...questions...answers...thoughts...experiences...nothing???

Well I ended up bi-amping the PPI355cs's a few weeks ago and when I went to preform the auto TA/EQ the HU didn't recognize the tweeters as the front speakers and gave a "Front Speakers ERROR" message. My guess is because they are not producing all or enough of the frequencies that the HU is trying to produce with them because they are crossed over above 200HZ through the passive x-overs which is the highest HPF the HU is capable of. So I manually input the distances from the woofers and tweeters to my headrest and it sounds pretty good. I noticed an immediate improvement in clarity from the woofers they are much cleaner but I still have them crossed over at ~250HZ @ -18db at the amp and my gains still need to be higher than I thought like 3/4 up. I have the HU front ch pre-outs going to the front ch inputs of the amp and then to the tweeter inputs on the crossovers and the same for the woofers using the HU rear pre-outs. Is this the best set up because I can set the TA for tweets and woofers separately or should I Y cable the front pre-outs to all 4 inputs on the amp so it can do its Auto TA/EQ and account for things that my ear can't?

The headunit will simply not accept the fact that the fronts cannot reproduce midrange sound, hence the error. I have not tried this setup before so i'm not sure it that is what is happening here. I think you should find a reputable sound shop near you so they can run a RTA sweep on your car and see how the AUTO EQ / TIME ALIGNMENT set everything. I'm thinking that when the Pioneer tried to test the latency of the sound the tone was not present because of the crossover setting too high, hence the ERROR.

Ok so What does RTA stand for? How much would that cost and I probably won't do it until I finish my install including new sub box and sub and probably custom door panels with a ported enclosure design for my speakers that I'm experimenting with right now, Literally. and thanks for the response

RTA = real time analysis

That pioneer unit should output 5volts(rms) for all preouts, make sure to turn off the FIE(front image enhancer) soundstage feature, that would focus the sound on the front, your question on the rear hpf I think your are trying to create a bandpass signal, which is blocking the bass on the deck at lets say 50hz while using the LPF on the amp but raising the crossover around 250hz, anyway say try it and see what you get, you can use y-adapters (splitters)if you that theres a problem or better if the amp has an rca output pass-thru set use that with a short set of rcas back into input of rear ch, this will save you the money of buying splitters only if output is available, last go into the pioneer functions with the radio off and check the rca rear output settings, I think you can adjust it to full/sub/etc... range. DANG, I hope you find some answers in this book I wrote, let me know.Chadillac