Hi, I can confirm that in the kona, we have some amp in the back. Don't know the power rating and how good it is. But compare from my olf Leaf 2013, kona is good stock. I have Canadian preferred version. BTW, in the leaf, the speaker doesn't has magnet just to tell you how cheap they were.
From my experience on the leaf, I Added ALPINE KTP-445U UNIVERSAL POWER PACK, because the console control everything like most EV today. And add the cheapest speaker. They were, not kidding 5x better than the stock one. Now, the sound was good with a really good punch. Didn't wanted a subwoofer from the bass perspective.
Now after all left door sound insulation on the Kona, the sound is better. Would say 30% better compare to the other doors that didn't do yet.