Something does not go well here and I don't know what. It reads like a lightly sparkling boulevardier but something about it makes it unfortunately quite undrinkable.
We think the problem here is that the balance between bitter (red bitter liqueur and Amaro) and sweet (Grand Marnier) is way out of whack. We tried two alternatives: one simply adding 15ml Carpano Antica (as a nod to Avery's Boulevardier); the other adding 15ml Aperol (I suspect that there is an unwritten bartenders' law that Aperol and Campari shall never mix in the one cocktail, but never mind). To retain the fun, we upped the bubbly to 45ml. A generous coupe glass will be needed. We think these versions, although perhaps a bit more fussy, are much better balanced, but possibly completely different drinks. We like the brooding nature of the Carpano version. Anyway, they restore the Negroni proportions of 1 base spirit to 1/2 bitter and 1/2 sweet.