Dynamic Subdivision Blended with Classic Subdivision
Using Dynamic Smooth Subdivision mode will generate a visual result that is exactly the same as a classically subdivided mesh, except that only the base mesh is editable. You can’t sculpt the displayed higher resolution surface.
Also, options like chamfering require angles in your surface to achieve the best results. Since Classic Subdivision smooths the surface, those angles will be lost and features that depend upon them won’t work as well.
While it is possible to combine Dynamic Subdivision with Classic Subdivision smoothing, it is generally advised not to. If you must combine modes, only do so at low levels.
Put another way, use Dynamic Subdivision while building your base mesh, prior to detailing. Once you have completed base mesh modeling, turn Dynamic Subdivision off and subdivide like normal for the rest of your sculpting. (Or use the Apply feature explained below.)