It actually confused the heck out of me initially, because the 950 that I had previously worked fine without one. Likewise, the 1070 and 970 also do not require an interface module. The issue here appears to be the fact that the 990 is based on an existing hardware platform (the Sherwood P-965), and wherever they could they retained existing hardware components. The hardware that Outlaw designed from the ground up in conjunction with Eastech (the 950, 1070, and 970) do not take this approach to the IR input jack. The need for an interface module is one of the few negative hardware traits carried over from the old platform.