I use ViPER4Android with a Dolby IRS.
Produces very similar results to Amazon's native implementation on FireOS.
I honestly can't remember where I found it, but I've attached the file to my post (inside the ZIP). You need to move it to /sdcard/ViPER4Android/Kernel.
Just set the UI to expert mode and enable the convolver feature. I'd also recommend turning on speaker optimization.