I want to pierce a wall so a network cable can go through to the next room. Will I ruin the sound insulation that way? How much of a problem will it be? Will I be able to repair the sound insulation afterwards?
No, a *small* hole mostly filled with a cable will not be a problem.
I would suggest that two wall mounted connection plates, joined by a short piece of cable within the wall, is neater. The hole can be smaller as it only needs to be the diameter of the cable, not cable plus plug.
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