Thanks Gonk.

This remains weird.

I press 1-2-3-4-5 and I get the same thing both with, and without, the mic connected: a perfectly flat sweep line running across the bottom of the graph - and all sliders sitting at their centered position.

When I selected "AUTO" instead of "MANUAL" nothing happened.

Something's not right here.

To review my very basic connections. I've got power to the unit. I've got a cable running from my 950 to the LFE input jack. I've got another cable running from one of the LFE outputs to my subs. And I've got the mic connected to the front input (I've tried the back as well - just in case). The unit is definitely putting out a sub signal (when I push 3-2-1) and it's definitely passing the sub signal from the 950.

But it does not appear to be doing anything at all to that signal in between.

I remain stumped.

Unless I'm missing something really basic here, the unit's got something wrong with it.