I use GABA and I find it works a treat but you really need to adjust your diet too to limit Glutamates which excite the brain. I use GABA with B6 for better absorption from NOW:
https://www.iherb.com/pr/now-foods-gaba-with-vitamin-b-6-500-mg-200-veg-capsules/14040
I've been avoiding the following foods. The ones with !!! really trigger me as they're full of Glutamates.
• MSG !!!
• Parmesan cheese !!!
• Shiitake mushroom !!!
• Soy Sauce !!!
• Pistachios !!!
• Walnuts !!!
• Tomato Sauce !!!
• Tomatoes !!!
• Mushroom !!!
• Spinach !!!
• Broccoli !!!
• Lentils
• Peanuts
• Peanut butter
• Cashews
• Plums
• Grapes
• Turkey
• Rabbit
• Anchovies
• Sourkreut
• Most cheeses
• Edemame
• Most canned food
• Ham, Salami, Sausage, Bacon
• Corn (Moderate)
• White Potatoes (Moderate)
• Peas (Moderate)
Also watch these
• Salt (Limit but do not eliminate)
• Onion and garlic salt
• Artificial sweetener !!!
I avoided salt completely for a while and my blood pressure dropped too much so be careful. Our body needs salt but not in the excess that we typically consume.
I've done a gut test this year and found to have very poor stomach microbiome diversity (low 10Percentile) which leads to poor natural GABA absorption, from what I've read. I'm hoping to improve this with probiotics and kimchi which boost GABA absorption naturally and hope tinnitus will naturally quieten down.
These are my personal findings and the list might slightly change over time. But definitely look into Glutamates and GABA.
Good luck, I hope this gives you some relief.