The other day I noticed the other day that an addition of orange bitters to a gold rumhattan mellowed it out - too much. Today I tried a black rumhattan with the addition of Regan's orange bitters, hoping it's more to my taste.
40 ml Goslings Black Seal, 20 ml Dolin Rouge, 1 dash Angostura, 1 dash Regans Orange bitters. After a few tastes I decided it needed some sweetness, so I added 1/2 a tsp (2.5 ml) of luxardo syrup to the drink. Tasty.

P.S. thank you Mr Difford for this site.