The standard ICBM has 120 Hz as its highest crossover frequency, and the CC1 and CC2 require something in the range of 160-200 Hz. I have a CC3 crossed over at 80 Hz, which is its rated value, and it seems to be fine. I have tried higher values and do not think I am missing anything at 80 Hz. I do recall reading one review of the CC3 where the reviewer preferred a value of 100 Hz, but this probably depends on placement and other equipment. In any case a normal ICBM, which you are more likely to be able to find used, or most processors should be adequate for the CC3.