Stock a/d/s stereo system - please help

[93 County]

Hi,
I recently purchased a 1993 RRC with the stock a/d/s stereo. I want to keep the head unit and have already replaced the (4) 4" stock speakers. Any and all advise, opinion and experience requested and appreciated regarding.......

- can you replace the stock ph11 amp with anything that is plug and play? Stronger? Etc.
- I was given a ph20 6 channel amp a while back. Is it compatible? Any instruction for installation?
- can you replace the sub with a new 8" in place of the stock 7 1/4" sub?
- what is the purpose of the dual voice coil in the stock sub?
- can you "add" an amp into the system to run just a separate sub?

I emailed Roverville twice asking about their upgrades and mp3 aux etc with no response at all. Any idea?

Thank you vey much.

[93 County]

Let's see what you've done!

After searching quite a bit, i am still having difficulty locating informative and consolidated information for stereo upgrades that work/make sense. i have a 93 with stock a/d/s system and ph11 amp.

Does anyone have any pictures of their stereo upgrades, changes etc. their amp and sub installation process or installed? do you know the purpose of the "dual voice" on the stock sub? i just looked and i actually have a 6 channel ph15 in mint condition to work with ~ which i understand to be one of the best. sure looks like i could run a box with my shallow Kicker 10" or a better 8" in the stock box and the rest of my speakers easily which i have upgraded. Any thoughts? Thank you!