I know this is an old post, but thought I may be of some help still

I use Dyes from Dharma for my black. I mix 50/50 Better black and New Black and it has given the best real black color, we actually get lots of compliments on our black.
In an 8 oz bottle we use 4 TBS of each kind though so it can be rather expensive. ALso once you have made your bottle of dye, I suggest slowly pouring the made bottle of dye into an empty bottle and rinse all of the sediment out of the bottom and then transfer it back into the first bottle, this will get rid of the fuscia that seems to pop out in the black.