want to upgrade my car audio .. no idea where to start

What do you feel is missing? Bass not hitting hard enough? Highs not clear?

What is your budget?

From what I know, having the JBL system does add some complication to the aftermarket upgrade process. I don't know the specific details, I came from non-JBL and did my own aftermarket upgrades and it was pretty plug and play (after tweaking crossovers and gains) after I got my extensions done up to intercept the signals in and out of the head unit.

I'd start by reading other people's upgrade journeys in older models, use that as a foundation for what to expect. You searched for jbl - black_jmyntrn

 

Yeah you likely don't need to upgrade for that usage case. In fact I'd start by trying to see if ALL audio from different sources (phone, xm radio, fm radio, apple music, etc) has the same issue.

If all sources of audio have some sort of distortion or crackling then you might just have a faulty head unit or amp or something. Because you shouldn't be getting that kind of noise normally.

If other sources are clean and it's just your audio books, then I'd start figuring out how to fix that instead of throwing money and parts at upgrades that may not fix it.