This is off the top of my head, so no citations, but d-methamphetamine is something like 30% more potent than d-amphetamine. The fact you're taking Adderall makes the comparison more complicated though because you're not taking d-amp. In general d-amp is 3-4x more cognitively powerful than l-amp. So we can consider l-amp to be about 25% the potency of d-amp, except IIRC the 75:25 d-amp:l-amp ratio of adderall synergizes a bit, so let's say that d-amp is ultimately 2.5-3x as strong as l-amp.
Your 20mg of XR addy is equivalent to 10mg IR and another 10mg taken roughly 4 hours after, but let's forget the XR part and just assume it's a 20 IR for convenience (it doesn't change the math anyway, just the pharmacokinetics).
20mg IR Adderall is 15mg dextroamphetamine and 5mg amphetamine. That's about 17mg dextroamphetamine equivalent. Given my estimate of d-meth being 30% more potent than amphetamine, you're taking an equivalent of about 13mg of d-methamphetamine a day.
> In either case, I've never experienced anything like a euphoric high, but I have experienced the kind of "uselessly driven"/tweaker sort of side of it. And, let me tell you, I do not like it when that happens.
See you're amphetamine tolerant. Give your 20mg dose to an amphetamine naive individual, and they will get the euphoria for the first couple days at least of taking it. The euphoria quickly fades, though.
You are correct that when you overdose and aren't stimulant naive, you often end up with mostly the downsides with little upside. There's not too much value in pushing the body past its "equilibrium" level of stimulation (in your case 20mg XR).
> Although I'm in no hurry to find out, I honestly find it hard to imagine what the high must actually be like in order for people to voluntarily subject themselves to the negative effects of this drug. And, I don't even exceed the therapeutic range when this happens!
> I wish there was some way to actually understand why people abuse meth without actually smoking meth myself, which I'm unwilling to do, for obvious reasons.
Have you ever done MDMA? That makes it easy if you have, because MDMA is like a way gnarlier version of methamphetamine: it's shorter lasting and releases WAY more serotonin while still being very dopaminergic. Methamphetamine, taken in oral doses enough to get you slightly tweaking but not at a crazy level, is kind of like 10% of the sensation of "rolling" (rolling means being quite high on mdma) while feeling like a smoother, less physically tweaky version of Vyvanse, which itself is a smoother, less physically tweaky version of adderall.
(For context, when comparing adderall to dexedrine to vyvanse, adderall is by far the tweakiest due to the l-amp. Personally, I'm a dextrorotatory supremacist so I won't touch the l enantiomer with a 10-foot pole)
If you've never done methylynedioxy-methamphetamine, and you clearly haven't done regular methamphetamine, you likely don't "know" what serotonin feels like, unfortunately. But the TLDR is methamphetamine is a smoother and somewhat more dopaminergic version of amphetamine, with the added bonus of some minor (significant when you're smoking it though) serotonin release as well, whereas amphetamine has almost no interaction with serotonin to the best of my knowledge.