Re pain: the brain "lacks pain receptors" according to standard thought (tho same can't be said for the meninges, so I guess all bets are off). Tho what about emotional pain? Increasing the signal/inputs might increase possible negativities (tho chips would probably monitor and adapt your "recommended content and styles" to increase pleasantness - taking "brain hacking" to whole new level I guess). And interfacing with it might might consume more "mana" making your brain hurt due to depleted resources. Idk.