Tuning from amp?
The controls in HU (if present) are electronic and on amp are mechanical. And the controls on amp are very limited. Just set the gains from amp and use all pass filter / switch off lpf, hpf.
Always write down your head unit settings for contigency. In case you lose the tune/ settings, the piece of paper can get you back where you were.
And if the head unit is basic than off course set filters from amp.
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