Orion 2100 hcca help?

When you say clipping, do you hear the subs clipping or the clip lights are on? If memory serves the 2100 HCCA has an unregulated power supply. Higher voltage/more output. Is the 11.4 Volts read while the vehicle is running? If that's the running voltage, you should upgrade the alternator and the amount of copper running to the amp. That amp will suck 100 amps no problem. Batties and Caps store energy, not make it! Another question, are you clipping the inputs and the amp is doing it's best to compensate? or maybe you are just plain out of power!! Not familar with Swiss Audio, but if the sub aren't very efficient you need more amps! The 2100 HCCA is a strong solid amp but it needs lots of voltage and current, especially at 1 ohm stereo! Just a few thoughts . . .

The Orion will want more current, it should produce around 1600 w rms at 1 ohm.  Some versions of that amp weren' t stable to 1 ohm stereo ( 1/2 ohm mono).  The amp maybe protecting itself from to much load.   The 225's would go down that low.  Double check your amp specs, rewire if needed.