Try to bridge it at 2 channel to power them passive. See whether it is adequate to your liking. If it is still not up to your expectation, then only change. My opinion is to maintain this Genesis amp and get a separate amp for the SW (if required). You may want to turn up some bass gain (if the function is available in the amp). But practise caution as u don't want to spoil your mid bass.
I'm not too sure whether the power is adequate in your case but many have forgotten the aspects of cabin gain here Time alignment will help in the bass aspect too (but not everyone is in favour of this tuning option). By the way, what HU are u using? If it's me, I will try all options from EQ, time alignment and whatsoever tuning options available before I change anything.
