need help with PA

Hi everyone, I'm a newbie here and have seen some pretty good advice given. So here goes my problem. Our band used to be a 3 piece (Bass , Guitar and Drums) started out just playing music and having fun. Well we added a singer and recently a rythym guitar player. Our old Pa was a mixer/amp combo nothing special a Electar 4 made by Gibson. Well We find ourselfs not hearing the vocals. So I have added a Nady XA1100 power amp and was wondering if i should use my Electar line out to the Nady or buy a seperate mixer. I'm pretty new to this whole PA stuff. I've looked a EV ELX mic mixer but not sure if that is what i need. Reverb is a big plus. We rehersal in a small 25 X 25 room. low 8 foot ceiling. Like every musician a budget is there but at the same time i don't want to buy someting now and replace months later. any advice appreciated thanks