Phenethylamine is an unscheduled non-psychoactive chemical that has no particular value as a drug precursor--in other words you can probably find it by the kilogram on Amazon. No point in going to the effort of synthesizing it, except for the sheer fun of doing chemistry... but then there are a lot of other syntheses you could do that would probably be more fun/interesting. Also, like I said, it has no particular value as a precursor. You can't simply add a methyl group anywhere on a compound--especially unlikely right there under the amine. But we don't do chemistry talk here.
Beyond that: Massive doses of phenethylamine--enough to flood MAO can achieve a stimulating effect. Also phenethylamine with a monoamine substrate like hordenine or b. cappi is a combination that's supposed to induce a very euphoric but very brief stimulant high. Selegiline also works, but is playing with fire: Yes, it's selective for MAO-B.... but it's also a higher affinity and longer lasting inhibitor of MAO. If you're intent on doing this, you're going to want to do this in the way least likely to end in a hypertensive crisis. That means use a relatively benign/inert chemical as an MAO substrate--like hordenine--combined with a progressively titrated dose of phenethylamine to get effect. Then cool it, and come back another time at that active dose level.
But really, playing with MAO inhibition just to achieve a stimulant effect is beyond absurd. You're adding a whole lot of risk of bodily harm in the case of error, for a payoff that's just not that great.
![:\](https://bluelight.org/xf/BL_Images/Orig_Emoji/wrygrin.gif "wry grin :\")
