Question: My Logitech speaker and my external HDD have 40CM between them….is this dangerous ? Will there be a mechanical failure because of vibration or magnets ?

Answer:When it came to preventing damage on external hard drives and better the chance for normal life time, you should focus on:
Avoid any motion or vibration, because of the delicate mechanic inside.Avoid placing the drive on a soft or moveable surface.Only turn it on when you transfer files to it, then turn it off.You can probably solve the issue by playing high music when the external drive is disconnected.