Found out that the Pascal module in the Trickfish is bridged internal to achieve the 1000watt@8ohm. So by connecting two 8ohm cabs it stopped, or only one 4ohm cab. It doesn't run a 2ohm load.
The VDK has two times the power of 800watt@4ohms, so you can connect four 8ohm cabs if you want to, or two 4 ohm cabs.
The module in de VDK is more powerfull and not bridged; more safe idea, but that's personal.