Hello... Most headphones with low impedance (less than 25 ohms, approximately) require little power to deliver high audio levels. For example, low impedance headphones will work well with equipment with weak amplification like portable music players, phones, and other portable devices.
Headphones with higher impedance (25 ohms and over, approximately) demand more power to deliver high audio levels. As a result, they are protected from damage caused by overloading. They can also be used with a wider range of audio equipment.
Your headphones are 50 Ohms.... Most low cost throw aways, can be as low as 4-8-16 Ohms and will sound louder VS your 50 Ohm Models.