in this case look at the db sensitivity differences.
when the rear sound propagates the loss in db from the rear door to the front ears will be about 2 to 3 db lower then the front. negating the effects of the seat blocking sound. So there will be rear fill but would not pull the sound stage back/ down. Also note the rear and front door speakers you can switch the tweeter -3db to also prevent pulling the sound stage to far back and/or down.
of course this is all theory crafting not actually having access to a spectrum analyzer like i had back in my stereo install days.
I have always been one and was trained if possible to build/design the system to be balanced as much as possible via install location, sensativity, aiming, passive network design/phasing before relying on processers fade/ballance eq ect to get the sound right.I see the sensitivity difference but I still don't understand why you would use reference series in the front and kappa in the back. You can compensate for the dB difference with the amp or fader. I would always put my best sounding speakers in the front. (or are there not kappa 6x9's available?)
There is a thread that shows this in detail...will link it when found.
Thanks to "sp8ball" & "Antman"...:hail:
http://www.toyota-4runner.org/774421-post389.html
You'll need to remove 3 screws before you can start yanking on the door panels. Be gentle
prying these covers open....the panels are very soft and scratch very easily.
While you are in there, change light to LED.
https://www.superbrightleds.com/mor...bus-led-bulb-5-smd-led-wedge-base-tower/1127/
Door Lights (35 lumen)
View attachment 79594
The 1st time you remove the Tailgate Panel, it will be tight. There is an arrow molded into
the lower/passenger corner. This is where you start pulling.
While you are in there, disconnect the tailgate cargo lights and install led panels.
Cargo Area Lights
View attachment 79593
The one on the left...(140 lumen?)
https://store.ijdmtoy.com/ProductDetails.asp?ProductCode=LED_9SMD_D31_SKU24
The one on the right...(70 lumen)
https://www.superbrightleds.com/mor...-bulbs/de3175-led-bulb-4-smd-led-festoon/238/
Some Good Tools to Have Handy...Less Than $20
View attachment 79592