The Quads benefit from the most dynamic equipment available, as they are not so dynamic by nature, it helps atleast to get the upper hand on dynamism upstream. I found that the CAT preamps are very dynamic. I had the Ultimate v1, which was very nice (even though CAT was not that much fun to deal with directly). They have older models that might fit your budget. In any case, my recommendation is "look for a dynamic preamp".
Best, Peter
Best, Peter