Another thing is if you have dopamine, gaba, serotonin or any other NTs issue, taking more precursors of that neurotransmitter will NOT work 99% of the time. The issue is usually with converting, discarding and releasing said neurotransmitters. You already get enough precursors from your diet if you eat a decent diet and enough protein.
It's better to take things that will activate or deactivate the receptors or things what will block or increase uptake into the brain. I had to learn this the hard way taking tyrosine, 5htp, choline etc..