Re: Need advice on 2011 Hyundai Sonata SE
From what I'm reading the DSP processor is basically like an external headunit. It plays from an Ipod and has an internal amp for speakers and outputs for other amps to expand.
It isn't very common to have a full home-theater type setup in a car. Most only run a sub and front stage. I'm not sure if a crossover setup even exists to produce and distribute full 7.1 surround sound.
There are a couple different options for adding more speakers.
You could add another amplifier to the system, using the preamp outputs from the DSP module, to power the 2 or 3 speakers you want to add. Another 4 channel amp would give you independent power control to the two rear speakers, and independent control of a center speaker.
The other way is to power the 2 extra speakers off the the rear channels of the DSP. However this may not be possible because you would have to wire two 4 ohm speakers in series which puts a 2 ohm load on the DSP (it probably wouldn't support that) and you only have limited power between 2 speakers and no independent control. Now way to power a center speaker either.
You may very well be happy with a good set of components (door speakers with a seperate tweeter) in the front and back with a good 4 channel amp to power them. The DSP setup you already have will support that expansion. Factory Door speakers are somewhat lackluster in comparison to what is available online.
Good components will really shine after you deaden the doors. I won't go any further because this is seriously an addictive hobby.
2002 Mazda Protege5
Rockford Fosgate 1050S
2 10" Powerbass M10s