Crossover Volume Level

I just built my own passive crossovers and found the volume level for the mids is too high. I know how to adjust this level with a resister, but would like to know if there is a way to measure the volume level output of the tweeter/mid/woofer to achieve a balanced sound without guessing and secound guessing myself. At a given volume setting, using a SPL/DB meter are there general guidlines as to what each speaker SPL/DB should fall in to achieve a balanced sound from the combined speakers. Thank you in advanced for your help.