Since I just got my 990/7125/LFM-1Plus combo installed yesterday, I've been messing around with all of the settings.
When looking at the Bass Matrix page, it says that when the Front Speakers are set to Large, and the Sub is set to LFE, the sub will get LFE+Sm Spearer Bass.

When the sub is set to LFE+L/R, it gets LFE+Sm Speaker Bass+L/R.

Why is that? I don't get why more bass "Sm Speaker Bass" is being added to the LFE (.1).

I played L.O.R.-1 earlier in DTS and swapped between the sub being set to LFE and LFE+L/R.
When in LFE+L/R, the bass was too overpowerfull.

There is no way I can see to get just the LFE (.1) to the sub.