I don't think in general a fuse blowing can be attributed to clipping. More likely, the speakers are just being driven to the point where the fuses blow. The amp may or may not actually be clipping when it occurs.
In any case, assuming everything is working as it should (no guarantee with older gear) most likely you are just asking more than the speakers are designed to handle.
If the fuse always blows immediately when the processing on the receiver is switched, then it might be due to some sort of noise or other electrical anomaly situation created by the receiver when the audio mode is switched. Try turning it down when switching then turn it back up and see if that makes a difference.