Let's get some of the preliminaries out of the way first: As you can see, I've rated 5 stars on every aspect of the unit, so that should let you know first off that it is well built, has a bucket load of features and it sounds great... so what else is there to say about it?
I use the Headamp 6 Pro in a small recording studio setup. I already owned a number of different pro headphones - Sony 7506's, Beyer DT100s and so on - but not enough to record a full rock band set up in a live situation, where the drummer and vocalist were isolated from the rest of the band. I looked at a number of the headphone amps out there at the time. I didn't particularly need 6 channels, but one feature on the Headamp 6 drew me to choose it, and that was the individual 'more me' inputs on the rear, and a Direct In jack on the front. With a 4 piece rock band to record, I bought the Headamp6 along with 4 pairs of Extreme Isolation EX29 headphones.
I started off with it wired so that each band member had an individual mix of their own, with each aux output from the desk sent to individual 'more me' sockets on the rear of the unit. It didn't take long for me to reset the whole thing so that the main inputs on the rear accepted the live mix I was monitoring from, with each 'more me' input now only recieving whatever exra each musician wanted to hear (...mostly just more of themselves, hence the 'more me' moniker!). This was much easier to handle from my point of view, and although it sounds like a compromise from the band members, none of them were unhappy with what they were getting in their phones, and with each of them able to balance the mix between 'main' and 'more me' inputs, I left them to set their own headphone levels and mix choice from the front panel. Everyone happy.
Lastly, as an audio 'notepad' the band had recorded their pre-session rehearsals on a Zoom recorder, and with this plugged into the Direct In socket on the front, they were able to play this back in order to refer back to any notes they made as they prepped for the recording session. A real time saver.
Top marks for this unit. Even after the rare event for me of recording a band in one go is over, the versatility of the unit means I can cater for anything coming in the door now. A great addition to any small studio, and the high quality for all aspects means it would also be good enough to cut it in bigger studios too.
Would I buy again if it was lost? Yes. In a heartbeat.