Yes, more neurotoxic because amph releases dopamine, which binds to serotonin receptors during the serotonin drop after and when MAO breaks it down it becomes neurotoxic there. You can help this by after having an SSRI or technically an MAOI, but that would kill you.
You can also help it a LOT with antioxidants and 5HTP post usage. I think this would be easiest and best for you. I also agree with dropping the amph by at least half for the roll eclipsing the MDMA and for neurotoxicity and because MDMA is still a stimulant.
You Could try taking the amph a little before hand, that would help not have DA pumping during the serotonin drop. 30min-1 hour I'd recommend. Also powdering the amph will help it die faster and hit stronger so that you'd have to use less anyway.
What are you using? Adderall? Maybe also try other stims instead of pat of the amp. But yeah, really recommend 5HTP and antioxidants, especially for what you're doing.