Does lower ohm impedance decrease sound quality?

When you lower your ohm load, your car amplifier and subwoofer/speaker will have less resistance between each other. This will result a advantage because it will increase the rms total power output, without buying a new car amplifier. The more lower the ohm rating is the more strain is placed on the amplifier, which can cause the amp to stress out, only if the ohm load is below recommended. If your amp has stress from a low impedance, it can destroy sound quality and clarity because it has to work much harder to produce sound.

The higher the ohm load, your car amplifier and subwoofer/speaker will have much more resistance, which reduces the output power of the amp. The more higher the ohm impedance, the less hard work its for your audio amplifier. However the increase of impedance will have little effect on sound quality, only and unless if your amp is designed to handle your higher ohm load.

So my point is if your car amplifier is designed to operate at a low ohm impedance, you will not loose any sound quality. But if your manufacturer says don't lower you ohm impedance and you do, you will loose sound quality and gain more spl instead.