Most Condensor Microphones have a "pad" switch (usually -15 or -20 db). That will decrease your input volume, allowing for you to turn your gain up and have greater ability to fine-tune. Also, most mixers have a "pad" switch or button as well, and this will do the same thing.
However, I have never encountered a condenser microphone producing such a strong signal that I literally have no need for a preamp... which makes we wonder if you have another gain stage somewhere in-between your mic and your mixer? because it sounds like your up at line level before you even hit your mixers preamp.