You would need a headphone amp. They are small and inexpensive. They can handle multiple sets of phones.
I own this one by Rolls. http://www.zzounds.com/item--RLLHA43
I also use the Rolls to amplify the headphone output on my e-kit brain.
If you buy the Nady powered monitor that I mentioned you can plug your phones right into that also.
I use the Nady when I gig as my stage monitor. I put it on a heavy duty 3 leg mic stand. It works great and I can control my own monitor volume and EQ.
I have a bluetooth receiver hooked to my Passport that allows me to wirelessly transmit sound from my laptop too.
The Passport is great for small room work. It has excellent feedback control and many features that make it easy and practical to use without fussing about.
I added a 10" powered subwoofer to my Passport fromJBL. It sounds awesome!