high input and low input

What's the different when making amp connection with head unit? there's an option that you can connect as high input or low input, beside wire differently, what else is different?

High level (speaker level) input is not as stable, does not have as good frequency response and is prone to miss some of the lowest freqs.  Use the line level if the deck has RCA preouts, and use high level only as a last resort (usually with factory decks).  In fact, if using a factory deck, buy a separate high quality line out converter and leave the amp's high level converter alone.

https://www.bcae1.com/loc.htm for more info.

-------------
Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Agreed. Leave high input alone.

-------------
EK Civic
security
no audio