CDA-254. The 4 suffix designates 4 ohm stable. Although he only publishes it as 500W 8 ohm bridged, he does confirm it will also drive 4 ohm when bridged. Power will be slightly more, but not double. It will start clipping (>1% distotion) long before 1000W.
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2 M80s, 1 VP180, 4 QS8s, 2 EP800s, 4 Algonquins, 2 M3 VaSSallos