Let me set the record straight, inside each and every magnetic platter style hard drive are two 1" wide by 2" long by 1/16" thick neo magnets that are strong enough to hold 20 pages to a fridge. In fact, with nothing under them you can't pull them straight off a metal surface, they have to be slid to a corner.
These drive the arm the heads ride on and are less than 1/8" from the platters themselves. So, no, a permanent magnet for a sub is not going to hurt a hard drive through two packages and a PC case. Besides, fixed magnetic fields aren't the danger to magnetic media, it takes an electromagnet to wipe tapes and hard drives.