I did a little experiment:
I diluted a CS whisky and measured the temperature. Albeit I used a so so thermometer, the changes are clear. And I used a pipette to add water.
So I poured 25ml of the Edradour bourbon cask 1st release at 57,4% ABV to get things started.
The T° of the water = 23,2°C or 73,8 °F
The T° of the whisky = also 23,2°C or 73,8°F
Then I started adding water and gave it a good swirl.
After one drop of water = 23,4°C or 74,1°F
After 2 drops = 23,6°C or 74,5°F
After 3 drops = 23,9°C or 75°F
After 4 drops = 24,1°C or 75,4°F
After 5 drops = 24,3°C or 75,7°F (0,5 ml water total at this point)
After 1ml of water = 24,8°C or 76,6°F
After 1,5 ml of water = 25,1°C or 77,1°F
After 2 ml of water = 25,2°C or 77,4°F
Then I thought adding more doesn't seem sensible any more. But when I continued adding water to my preferable drinking strength for this one (which must be around 10ml water in total) and measured again just out of curiosity, it was 27,2°C (or 81°F)
Now I decided to waste this dram for the sake out of curiosity, and the max T° I got was 28.0°C. I think I added around 30ml (rough estimation, I stopped adding measured quantities) in total now. But this isn't something sensible to do as I'm drinking whisky flavoured water at this point. Nosing this still works in a way, but it's all very flat and hard to define the aromas that are coming out. (I heard stories though that people at masterclasses learnt to dilute the whisky to 20% ABV to nose the whisky properly)
Of course you can get even more warmth generated by warming the whisky between you hand palms, but because you don't diluted it is still too dense in my opinion. So the combo of adding an amount of water to dilute, to generate warmth, and then warm it between your hands is probably best to get the aromas?! How do Murray and Paterson like that?
But my experience tells me that when you warm a whisky between your hands, you should finish it faster as it dies in the glass faster, because everything evaporates much faster. So I'm not a fan of that.