Hybrid vinyl planks come with acoustic underlay attached to them. For example the one that I am after has
LnTw of 40 db.
The question is if I install that on top of an extra 2mm acoustic underlay, say,
LnTw of 50 db, does that make a better soundproofing in an apartment with concrete floor compared to installing the vinyl plank with its own attached underlay? Or does that make no difference?