Jason
Hi Jason,
You mentioned that the preamp voltage from the head unit RCA output to your amplifier is only around 0.05V, while it should ideally be 2–5V. Based on your testing method, here’s an important clarification:
Most Android head units’ RCA pre-out signals are designed as low-level outputs specifically for external amplifiers. If there is no amplifier or load connected to the RCA output, the voltage on an open (no-load) output can be very low (a few millivolts to tens of millivolts), which is normal and does not indicate a problem with the unit.
Once the amplifier is connected, the output voltage should reach the design range (2–5V), and the system will work properly if volume and gain settings are correct.
We recommend confirming the amplifier is connected and its input gain is set properly before measuring the RCA output voltage.
