Presonus HP60 6-Channel Headphone Mixing System

They’ll love your headphone mixes.
Each of the HP60’s six headphone amps has its own level control and is loud enough to drive the alligators out of the Louisiana swamps. And the HP60 lets you customize each mix. In addition to the two pairs of main stereo inputs, you get an external stereo input with level control, mono, and mute for each headphone channel. So you can send each musician a feed of just their instrument or voice and can control the level separately for each.