I needed a basic 4 channel headphone amp for my home studio so I went ahead and bought this. It does exactly what it says, a nice 4 channel headphone amp, perfect for recording bands or when there are more than one artist recording at the same time. There is just the 1 input so as I said it is basic, the 4 outputs are going to be all the same, the mix will be the exact same in all sets of headphones. Its a nice unit, solidly built and the level knobs work perfectly, I never really have to turn any of them past 1 o clock, as they are plenty loud. If you are looking for a no frills headphone amp to add some more headphone outputs to your usb/firewire interface then this is perfect for you. If you need various different mixes for each set of headphones then you probably need something more expensive.