I have a head unit with 1 set of RCA plugs can hooking 2 or more ams hurt the head unit?

Answer 1

Nope. Using RCA splitters for additional amplifiers is very common. I wouldn't recommend splitting the output more than once, but even if you do it shouldn't damage anything.

Many amplifiers have RCA outputs as well as inputs, so instead of splitting the head unit output you can just run an RCA to the first amp, then another from the first amp to the second.

To those below: splitting a head unit output DOES NOT split the output voltage. An RCA splitter is just another example of parallel wiring; and in parallel circuits, the voltage remains the same and the current draw increases. Any voltage drop is just a result of increased current reacting with the head unit's output impedance, which is one reason why lower is better when looking at output impedance specs.

Answer 2

It will not hurt the HU, but everytime you split the RCAs, you split the output voltage. If the amplifiers have a RCA out, use that instead. Higher output voltage takes some of the work load off of the amp and will give you a cleaner sound with more headroom.

Or you can use a line output converter on the speaker wires.

Answer 3

The preamp outputs (rca's) are not amplified by the head unit. Therefore by running multiple amps off 1 set of preamps will not put any strain on the headunit.

Not amplified to the extend that it amplifies the speaker outputs anyway.

Answer 4

NO it wont hurt the system. the pre amp outputs of the unit are usually between 2-4 v pre out. this is the voltage of the audio signal to the amp. While higher the voltage the better , but amps have limitations in its input voltage. If you split it with a Y-type RCA cable, the voltage will divide since there's more cables now, probably will have to tune the gain for the changes in the amplitude the voltage.