What speakers will satisfy impedance requirements of amp?

Does anyone have experience in what replacement speakers will satisfy the impedance requirements of the stock upgraded JBL/Nav amp, giving a balanced signal (without center speakers)?

If I can not replace the amp until someone introduces a new amp that will replace the stock unit, I at least would like to replace the door speakers (an add a sub).

I have followed all of the positings here and have not seen the goal of finding speakers that match the original impedance addressed.