Woofer cabinet care?

Is it best to use a wax or oil on the wood cabinets?

I have a pair of Spires in natural cherry.

I would guess that ML uses a catalyzed lacquer on their cabinets. There really is no need to add anything to that surface. For cleaning a very slightly dampened cotton cloth should be all you need.
Some people like the look of a waxed or oiled finish. If you go this route you will need to keep up the maintenance of that finish as it will attract dust and dirt to which ever product you apply.
I would suggest trying a small spot to see if you are going to like the look. If it is the look you want either would be fine on them.

Are you talking about the new or older matte black cabinets?