Unless you want to wipe dye directly on the ash, (which I've read doesn't work our very well with ash)the sealer shouldn't be a problem. You should see if you can find out what kind of sealer MM is using, and if there are any compatibility issues with the finish you want to use. If there are not compatibility issues...just leave the sealer...it can be a real pain to sand off. You should be able to grainfill right over the sealer. This should highlight your grain. Then add some black Color tone or Transtint dye to your clearcoat...this will give you the black tint. Once you have the shade of black tint you want, swithch to straight clear to finish building your finish.