What setting should be used on a DMM to find voltage drops on amplifier grounds?

To measure voltage drops on amplifier grounds, the correct setting on a digital multimeter (DMM) is DC Volts. This is because most car audio systems operate on a DC power supply, and the grounds should ideally be at the same reference voltage. Voltage drops occur due to resistance in the ground connections, and using the DC Volts setting allows you to measure these differences effectively. By measuring the DC voltage across the ground connections, you can identify if there is a significant drop caused by a poor connection or excess resistance, which can lead to performance issues in the audio system.

The AC Volts setting is primarily used for measuring alternating current and would not provide relevant readings when assessing a DC powered system. The Ohms setting measures resistance rather than voltage, so it wouldn't indicate the voltage drop across a ground connection. Lastly, the Continuity setting is used to check if a circuit is complete, and while testing ground paths can be important, it does not provide information on voltage drops, which is essential for diagnosing audio performance issues.