Honestly, I don't know how high your tolerance is, or how good your dope is. 10mg morphine IV'd
But it's vitally important that you do not take Xanax with the morphine, or really with heroin either, it raises the risks of fatal CNS depression most notably, respiratory depression. It's a lethal combination man, people use it to seek the nod, but too many people nod out on that combo and never come back.
IV morphine is very similar to heroin, heroin is just a supercharged version of morphine which crosses the blood-brain-barrier (BBB) at a much faster rate, hence the infamous rush of IV heroin.
I would imagine if you have a decent tolerance it might feel like 20-30mg oxycodone. Equivalency charts usually give the 10mg morphine IV = 20mg oxycodone, or 30mg oral hydrocodone, however my personal experiences with IV morphine ampoules/vials like you have, it feels stronger than if you had prepped an equal dose of morphine from pills.
Tread carefully!