Learning what the Sound Edit setting do

[maintech]

I'm trying learn about the way sounds can be edited on my pa600, but don't know where to start. I have modified styles & songs using the menues to add or delete instruments, rhythms, tempos, variations, STS settings, pad options etc so I feel confident that I construct additions to my Songbook doing that. However I'd like to explore the stuff behind the sounds that I select, and adjust them if possible.
I do not have a critical ear to identify many of the differences that apparently are there, so what should I be trying to adjust that makes easy to hear differences? (several guitar & piano sounds on the pa600 seem to me so alike that I cannot make a rigid choice).
Is there a book, on-line AV or another tool that I could use to learn what and why is possible?
In my previous post re Fender-Rhodes I obvoiusly was asking a stupid question, because I assumed that built-in guitar amplifiers could be placed in the sound chain of the pa600, much like the early reverb addons that changed the room shape/size simulations were added to electronic instruments like the Rhodes.
Any info will be much appreciated.