Low-impedance headphones are in the range 16 to 32 ohms and high-impedance headphones are about 100-600 ohms. As the impedance of a pair of headphones increases, more voltage (at a given current) is required to drive it, and the loudness of the headphones for a given voltage decreases.
Yes, taking to much Vitamin D can cause some people to get diarrhea. Some others may experience constipation from to much Vitamin D.
The current tolerable upper limit of vitamin D intake is 50 mcg (2,000 IU) per day. Taking too much vitamin D can cause nausea, vomiting, decreased appetite, constipation, weakness, and can raise blood levels of calcium, which can lead to irregular heart rhythms. Previous question: