Thanks for the reference Randy. I found the forum discussion very informative. There are several posters including Gene who cast doubts about its effectiveness below 100hz.
"...would opt for the PEQ of your sub over what Audyssey is doing for bass. So far our experience is it either does nothing below around 100Hz (original firmware loaded in our 5805 review unit) or causes more problems than in solves (latest firmware currently undertest)."
I think it does a very good job at the higher frequencies but I've rarely seen an automated setup of bass that was optimal. Maybe the latest version addresses it, I don't know.
