The Behringer headphone amps are fine. Don't forget they're not in the signal path you're recording so as long as you get an okay sound in your 'phones it's enough. I have a Behringer HA4700 and a smaller (but much more expensive) one I bought second hand. I'm hard pressed to hear any difference...and the choice of headphones makes a much bigger change to the monitored sound.
Although the conversation has moved on, I'll just chime in that 100' is nothing in cabling terms. If you think about the circuitous cable route that would exist from the far side of a large pro studio back to the control room, that's often well more than 100' by the time it goes up into the ceiling or round the cavity walls or whatever. In live sound, think of how far it is from a stage to the mix position in an arena or stadium...way more than 100' usually.