If the bottom *isn't* flat, then the stand must also have an angle on it to match the taper on the cabinet. There would certainly be people who would want it firing straight out, where others might want some angle to get the best performance. My guess, and that's all it is, would be a taper on one side equal to or similar to the inclusive angle on the M80.
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A person convinced against their will is of the same opinion still.