Tried n-acetyl-tyrosine (500-1000mg) taken in the morning on a long learning day, no dramatic effect for me. So it should be at least an individual varying thing. Ergots (vasodilators) are something totally different, but for some (well, in my subjective experience) they help mimic a state of being in very good shape exercise-wise with the added learning/motivation increase.
Actually, what about sane use of ephedrine, e.g. at a mild 20-30mg/day threshold? Is that at least safer and healthier than amphetamines? Really, I'm curious, I don't know, but after all, the herb itself has a long tradition and as far as I understood the adverse and lethal effects occur mainly due to abuse/overdose?
For some less practical daydreaming: If you're unfamiliar with hedonisticimperative.com, it makes an interesting (LONG) read, going beyond pure nootropics (cognition-enhancers) to enhancing other aspects; there's really no clear cut border between learning, reward and emotions, so controlling those aspects holistically might be promising for enhancement beyond AD(H)D.
Hedonistic Imperative bets on future, safer/nonaddictive derivates of MDMA, citing two existing examples of research drugs,
PMMA and
TDIQ. That sounds promising, IF it will be safe and effective enough in comparison to existing stimulants. Personally, I don't know if we just run a bottleneck of chatoic-evolutionary brain layout with any of today's available approaches, which can't be tweaked indefinitely by treating it as if it were "soup" instead of the "circuitry" it is.