I use 4 of these for live recording sessions. They're connected in "mono" to 4 line outs of my antelope interface. I was worried they wouldn't be powerful enough to drive headphones, but they're actually extremely loud with sony MDR 7506's. In a nutshell, they provide a great alternative to digital IEM systems at a fraction the cost! I totally love them, and again at that price point, there's nothing you can complain about. If I wanted to be nitpicky, I'd say the volume button comes off too easily, and the clip is quite rigid. But I don't care, they serve their purpose perfectly.