Can a box cause clipping?

The box has absolutely *nothing* to do with the signal from the amplifier. In fact, in terms of any sort of normal operation, *nothing* you could do to the enclosure would have any impact on the amp, at all, no matter what. The enclosure determines how the woofer interacts with the air around it.... the signal coming from the amp is a total different can of worms. 'Clipping' has to do with the way your gain setting interacts with your head-unit..... it means the amp is providing a 'clipped' signal (that is, a signal with squared off waves instead of the beautiful dips and troughs of a sine wave) that inherently contains distortion. NOW.... in terms of enclosures... certain boxes/box types really *will* make the difference in terms of audible distortion, but that has to do with a particular woofer's *mechanical* power handling limits... for example, a sealed enclosure provides and excellent 'air cushion' for the woofers' operation... therin the speaker will be able to handle more electrical power input that the same speaker in a vented enclosure... where the air does not have the same "cushion".... even tho the input signal may not be 'clipped' in either case."I'm finished!" - Daniel Plainview