What causes clipping?

I am trying to understand why my Kinergetics SW-200 subs are clipping so easily. I had a thread in "speakers", but realized this "tech talk" forum might be a more appropriate forum to help me understand what actually causes clipping.

I am mostly using my system for home theatre with a HK AVR300 receiver and pairing the subs with Spica TC-50's. The Kinergetics seem to be easily overwhelmed when "bassy" scenes come up in movies. But, other than when aliens are landing, they don't seem very loud.

The Kinergetics have their own 150W x 2 amp which is fed from the pre-amp out on my HK receiver. The receiver only has a mono pre-amp out, so I am splitting that to the L/R Kinergetic amp inputs.

What I am calling "clipping" is when the subs make a fast, loud, popping noise. A fuse in the Kinergetics sub may also burn out if this goes on for a long time.

1. What causes the clipping? Is it the sub amp being overloaded or is the speaker itself in the sub being overloaded?

2. Would a bigger sub amp solve the problem? If so, any recommendations?

3. Can clipping be caused when the amp can't get enough current to power the speakers? For example, I have the Kinergetics amp plugged into the switched AC outlet on my HK receiver. Can the amp be overloaded as it tries to suck the power it needs through the AC cable maybe causing a dip / spike pulse to the speakers?

4. Does room size or speaker placement have any affect on clipping?

Thanks for the help.
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