So if I play [[Impact Resonance]] and play 3 [[lightning bolt]]s all at once and it was the greatest combined amount of damage. So would the damage I do be 3 cause of separate triggers of damage so different sources or 9 cause it's the greatest single combined amount of damage cause all three lightning bolts were on the stack together?

Another example:

Let's say [[Niv-Mizzet Parun]] is on the battlefield in Commander and I play [[Enter the infinite]] to draw 76 cards from my library to deal 76 combined damage with every draw trigger of Niv-Mizzet's ability activating. So would Impact Resonance deal 1 damage for the single damage for each separate draw of a card or 76? Cause it a combined total since it all came from one source Niv-Mizzet