Behringer HA6000

It does what it's supposed to.
If you are looking to connect up to 6 headphones to the same audio source you can do that with this amp. But you can also use each channel individually. Each Channel has 4 knobs to control the bass, treble, source and level. The knobs feel very smooth and responsive. The overall build quality doesn't feel cheap and is very stable. I didn't have any problems with it so far (about 4 months) and each input and output works.
The sound is decent, but you will hear audible noise at higher levels. You won't hear it through loud music though.
If you are looking for a cheap Headphone amp that will power many headphones, I highly recommend this one.