I use AVIA's 200Hz-20Hz sweep tone to judge how well my bass management system settings are doing. A sweep allows you to listen to the transition through the LFE setting, rather than just a single LF tone. As 80Hz is fairly unidirectional, you would have a hard time accomplishing anything with a fixed tone, except to verify that the sub and/or main speaker was indeed firing.

----- Clint DeBoer http://www.audioholics.com