I have the 2023 Sportage PHEV with the Harmon Kardon and hopefully the info I have also applies here. Even with the Harmon Kardon sub, the bass is pretty weak although with some media it's better than with other media.
I'm thinking of adding a powered 10" sub under the driver's seat doing something similar to this video for a Tucson (very similar to Sportage):
The video used this sub/amp combo unit:
LOPRO 10" powered sub
This one might be better:
Kicker 10" powered sub
Here is a document from another Sportage forum which describes the pinouts and how to open the panels to access the wiring:
2023 Sportage Audio Install Guide
I'm thinking of using the front door speaker line inputs which can be tapped from the amplifier under the passenger seat or from the inside the doors. I prefer to tap the amp since it's more work to open the door panels but the cable is pretty tight at the amp for tapping signals. So I was thinking it would be nice to find or make an adaptor cable female to male with short (about 6") wires so I can plug the harness #2 (see above document) into the adapter and plug the other side of the adapter into the amp. That way I could tap the adapter cable and make the whole thing easily removable so as to not risk voiding the Kia audio system warranty.
The document says harness #1 is 28 pins and #2 is 26 pins, but they both look to be 26 pins to me. There are 8 pins in two 4 pin rows on each side and 10 smaller pins in two 5 pin rows in the middle of each connector. For harness #2 all wires are on the left 8 pins and you only need to tap four of those pins.
If anyone knows where to find an adaptor or the parts to make one, please let me know.
