I'm assuming you got an offer from a big4 and considering it against another firm.

First, is this smaller firm well known at least in the industry its in? Even though the pay is crappy, big4 is a relatively good starting point. You can always jump between big4 and get a pay bump each time. By your 4th or 5th year, with enough luck, you could be bringing in 5k to 6k and sometimes 7k.