Small mixer with a headphone amp, as Shniggens mentioned above. Does your drummer play acoustics or electronics? That may be the limiting factor.
I used to believe both guitarists and drummers had to play at a certain volume to "get into it". A couple years ago I auditioned with a SLC band called "Zion Tribe", an excellent group of musicians. The drummer just smoked, but he did it at a volume so low that everyone sang acoustically during rehearsals, no mics set up at all. Wish I'd made the cut...
"Eccentric language often is symptomatic of peculiar thinking" - George Will http://www.puddlestone.net