So you have much of the hardware already, but you want to make changes.
Not sure why you need two threads.
Anyway, can’t you just get another one of those “LSI RAID cards” that work great for you right now?
I’m trying not to be triggered by your usage of the word RAID and just say that, as per the official recommendation: If you’re using a controller, use an HBA. Do not use hardware RAID. One set to “JBOD”-personality may or may not work as you expect, ymmv.
A system integrator would be able to tell you this. So would the hardware guides.