The Model 950 does have bass/treble control (see page 23 of the manual), and the Model 990 probably will as well. Outboard EQ's in the home theater environment are very rare - you have up to eight channels (seven speakers plus a sub) to contend with, so the cost and complexity of adjustment are significantly more than in a stereo arrangement. The most common outboard EQ systems employed in a home theater tend to be focused specifically on the subwoofer signal (which allows you to address the lowest frequencies fairly easily), and there are a few such devices around - one of the most commonly used is the Behringer Feedback Destroyer (or simply the BFD) although there are others. Here are some instructions on using the BFD to EQ a subwoofer.