Why don't the output voltage LEDs come on?

The LEDs show the voltage at the output of the product. There are several items that effect this voltage level. For example: With the Input and Output level controls set to maximum on the EQL/X it requires 0.25 volts (250 millivolts) on the inputs to make the 2 volt output LED light. If the LEDs still don't come on with the head unit at full volume and the Input and Output gains of the AudioControl component at maximum, your system will still work fine. You simply have more headroom to use. You can always add a line driver like the Overdrive or Matrix to increase the signal from the head unit further.