I use 3 daisy-chained Behringer Powerplay Pro headphone amps. One in my control room and two in the subterranean live/drum room. I use one headphone mix for everybody at the moment and the Behringers hold up really well. I connect them with Mogami cable via XLR and the performance is very good, never a failure and the sound is o.k too.
Headphones amps are workhorses, that's the LEAST place you need esoteric hi-end sound and as long as they keep working I'm fine with these. The price was about $ 100 each.
What I did was invest in 5 pairs of Sennheiser HD-25-1 headphones though. Now THAT will make a big difference. In the past I almost always totally hated the cans provided in most studios and thus the sound sucked too. The Sennheisers on the other hand are amazingly powerful and full sounding. It really helps with the performances and they also work great for making mic adjustements in the line of fire of a roaring Marshall or a Bonzoesque hitter.
Andi
www.doorknocker.ch