QUOTE(WindDragon @ Jun 10 2020, 05:02 AM)
Ok lets say i want to install JBL STAGE 600C Component speakers.
And these are 2.5 Ohms....2.5 Ohms seems low for car power supply.
Will installing this directly into the Head Unit without amplifier, cause overheating and burn down the car?
they manufacture the lower ohm speaker to let you enjoy the music at a "minimal number" of volumn increase, so you will think the spk are "low volumn" but sounds great!!

you headunit will be able to use with the speaker, but just don;t blast it always or the headunit will gonna blown. Its only for normal upgrade, not for hardcore / loudness freak.
if you want to use it with an amp, then why not get a 4ohm speaker which reduce the distortion at lower resistant?
i always suggest getting a 4ohm speaker to reduce the distortion from a power source, since most amplifier are still good at 4ohm, go for the safe bet will be more desired.