OK. So assuming then that do already have the 2-channel offset at the maximum (0 dB), your problem does sound very odd. I know, sympathy doesn't help much. :-(

Sorry, but just to eliminate any crazy obvious things:

You are using digital connections for both your CDs and DVDs, right? If you were using your DVD player and its decoders into the 990's 7.1 analog input, then all your DVD player settings come into play too. (For those of us playing DVD-A and SACD through 7.1 analog, the player's levels are all set flat when using the 990's bass management.)

There was a bug in the first release of the 990 firmware update if the sub calibration level was set at -15 dB, but I assume you are not there anyway, and you probably have the second release anyway. Just something to eliminate.

I have never heard of any DVD player that can manipulate channel levels before sending out the digital signal, but that would be only other place to look. I do remember some discussion around the saloon of some universal player doing something odd with a weak sub level in some mode. Maybe Gonk remembers that? That was still probably analog output though. Hmmm...

It is hard to imagine that crossover settings could have this kind of 6 dB problem. That is pretty extreme.

This could be a question for Outlaw support--like a blown IC somewhere? They are very good and helpful.