As I understand it, diet has not all that much to do with glutamate levels. Your body very rapidly metabolizes it (they do studies where they stuff people full of glutamate while repeatedly checking their blood, and it takes a nauseating amount to see a plasma glutamate spike), and the blood-brain barrier is impermeable to glutamate.

No, your answer makes sense but your are being fooled. Tofisopam is not a benzodiazepine. It is what we call a 2,3 benzodiazepine. This is an exception that makes it radically different than any other benzo. It does not directly bind at GABA-A like e.g klonopin and is a weaker anxyolitic. It's action mechanisms is very atypical, it acts as a PDE inhibitor, as a GABA PAM and as a dopamine presynaptic antagonist, making it mildly stimulant. The effect on phopshodiesterases give it unique pharmacology including neuroprotective effects.

Therefore this study shows effectiveness that is theoretically higher than regular benzos. I don't think that regular benzos or tofisopam block the AMPA receptors, although their increase in inhibitory GABA has a similar effect. It would make sense to combine benzos with an NMDA antagonist such as e.g memantine in order to reduce excitotoxicity (or weaker ones like magnesium l-threonate)

I advise you to try tofisopam (grandaxin) especially since it is a safe and extensively studied drug. Tofisopam is for sale in the U.S, OTC in practice e.g on rupharma, cosmicnootropics, possibly indiamart, etc You should not take it in combination with klonopin nor any other drug without advice from an expert (spoiler almost no-one is qualified) as interactions are possible. E.g it is a CYP inhibitor like grappefruit juice. note that the dose escalation must be very slow since tofisopam slightly increase heart contractility which can give non-dangerous but scary transient heart palpitations for a limited subset of the population.

There are many interesting neuroprotectants/modulator e.g BPC-157, cerebrolysin, etc However the most promising treatment besides tofisopam, is a drug that is only available in japan: https://www.semanticscholar.org/paper/Effectiveness-of-Celep... It is likely that tinnitus is already a solved problem, but no one knows it yet besides a few retired scientists.

A complete pharmacological response would also look in synaptotrophics and in mitochondria targeted antioxidants, such as SkQ1