There is an easy way to test this...get some test tones that hit only one speaker and test the response. If I want to check that my LFE is still going to 120, then I need some LFE test tones up to 120hz. If I want to test my fronts to make sure I have a smooth transition, get some test tones for the fronts only. Are there any test tones that I can buy that would do this?