The manual states:
Ideal for virtually any home or project studio, the HeadAmp4 easily adds additional headphone outputs to any mixer, computer audio interface, workstation, iPod, media player or laptop without creating any additional load on the existing headphone source. Capable of driving up to eight sets of headphones using a combination of 1/4-inch and 1/8-inch TRS connections, the HeadAmp4 can easily accommodate a variety of headphone models with varying impedances
So am I right in understanding that this supports varying impedances connected at the same time? Each channel has its own volume as well.