Back in the early 1980's I received a very nice coffeemaker as a gift. (Okay - it was very nice for the 1980's.) There was a small recipe booklet that came with it that had a great recipe for Irish coffee in which the Irish whiskey was put into the carafe along with superfine sugar and then the coffee was brewed into it. After the coffee finished brewing you would stir it and let it sit on the hot plate for about 10 minutes and then pour, top with whipped cream, and serve.
It was so good! It seemed to have more depth to the flavor and no hard edge on the whiskey. Smooth but not lacking in any way.
The recipe booklet is long gone and I can't remember the details of the recipe. When making Irish coffee the standard (for lack of a better word) way, adding Irish whiskey to a cup of coffee, I usually add 1-1/2 oz to 2 oz whiskey to 6 oz of coffee. (Depends on what mood I'm in or who I'm serving it to.)
I want to try the brewing method again so I'm wondering if I need to use more Irish whiskey to get the same flavor. I hope someone has an answer. If not, this could be a fun experiment!