I tried plugging my headphones directly into the 1/4" plug on the front of my C48 preamp and it sounded terrible - at least as far as hi-fi is concerned. There was no comparison connecting the line out on the preamp to the line in on the headphone amp - the sound was amazing!
I was mentioning in my earlier post that the only manual task I had to do before listening with the headphones was to turn off output 1 that feeds the power amp. Well McIntosh makes that too easy because that function is on the McIntosh remote control (which I never use).
I have heard a lot about the Sennheiser HD800s in that the name comes up often. Depending how much use my present headphones get, at least I now have a gift suggestion for my wife the next time she asks!