[JetBadger]

Possibly if implemented right. However for it to make any more sense than deck power, you need more voltage, 24V for example. Boost converters might work. Then you will have ground loop issues anyway, because the input circuitry on all the cheap boards is crap and not meant for car audio. Gains are set with resistors and changing them would be a pain in the ass aswell.

Eitherway do not use them. Premade boards will not work to your expectations and making your own circuit is, well... You're not saving any money vs. just getting a simple car audio amp for sure with either option.