amphetamines release vast quantities of biogenic amines such as dopamine, NE, and sert in addition to the other effects it has such as binding to DAT. however, like amps, opiates also increase extracellular levels of dopamine and sert. despite both drugs leading same result, they have different mechanisms of actions explaining why they release these monoamines.
when taken together (amps and opiates) the spontaneous release of dopamine and sert from each drug synchronizes to exponentially increase extracellular dopamine levels caused by each drug. in other words 1+1=3
so in theory if one wants to combine amphetamines and opiates, taking less of each is advised to get optmial results. for example, if you usually took 50mgs addy alone to get high, or 50mg oxycodone by itself to get high, you would cut each dose in half when combined such that instead of 50 and 50, you take 25mg addy and 25mg oxycodone
although amps decrease sedation caused by opiates, they definitely increase the euphoria in theory. for myself, i LOVE LOVE LOVE LOVE taking hydrocodone or suboxone with amphetamines, the feeling is fucking awesome! however because oxycodone makes me stimulated enough, i feel like it doesnt synergize well, like i just feel high on oxy and high on amps, not feeling super high from being on both.