The speaker emulation on our SansAmp products is part of the overall sound. It's designed to work with the speaker cab as well as for direct use. We don't use a steep brick wall type of roll off like some modelers, more of a gentle curve that still leaves the high end intact but avoids the "fizz" that you would get running an uncompensated output to the board. Real speakers don't eliminate all frequencies above a certain point they just start to roll off but are still present. Below is the frequency response of a Celestion 10" Bass Speaker.