Can I hook up a headphone amp to my integrated?

I am interested in getting some nice headphones. I currently have a Line Magnetic 518i integrated amp. As far as I know it has 3 line in inputs which now has my cd player in one, my phono preamp in one, with one remaining. It also has 1 preamp line out. The amp has no headphone input? I mostly listen to vinyl (90%), and sometimes cds as well. I would like to get a nice headphone amp and hook it up to the LM so I can listen while playing records and cds. Can I do this, and how would I hook it up? Can I just hook it up to the remaining line in input? I would appreciate any help I can get on this....I'm a bit confused if this will work, and if not, how can I go about getting a headphone amp working so I can begin to listen to headphones again?  (I originally posted this on the Analog forum since that is where I most "live" but this is probably a better forum).

Thank you all for your help!