?? Note on Impedance/OHM ??The more powerful your headphones are, the more likely they require an amp. I am a bartender and frequently work 8-12 hour shifts that require a lot of walking, running, hitting my step goals and constantly being on my feet. You have to go hunting for the recharge socket a little - it lives underneath the foam earpad on the right hand phone. I made the purchase of wireless headphones and when I tried them for the first time they worked correctly but when I connected them to the base they did not charge, the headphones were discharged and the charge does not work, when I connect the cable, with a 5V and 1A charger (which is the recommended), an orange light keeps flashing and after one minute it turns off and does nothing else. I highly doubt it?ll last much longer. simple to use & easy to move about. They are basically too big to hold things like a 3-way allen wrench without it leaning over and falling out easily and too small to put a handle of a wrench or cable cutters in- Im not exactly sure what the engineers designed them for. Since I was on the squat rack for a considerable amount of time, Im not too concerned with the application of the item. I didnt think I had to check for this feature, I assumed it was a given. If I had one negative, I would say that I tend to slide forward in them so after many hours of wear, my toe was sensitive to the front of the shoe - but for the price and comfort, these are great.