From what I remember, your CXC300 is a single channel amp, capable of putting out 300 watts into a 4 ohm load, and 175 watts into an 8 ohm load.

You can only connect a single 4 ohm cab to the amp. Two 4 ohm cabs would result in a 2 ohm load and potentially overheat and destroy your amp.

You could connect a 4 ohm 410XST to your cab and drive it with the full 300 watts.

You could connect a single 210XST to your cab and drive it with the full 300 watts.

There are quite a number of Eden dual channel amps that could drive both of the 4 ohm 210XSTs at the same time. The early WT800/WT600/WT500 series are all dual channel, and capable of driving a 4 ohm cab on each channel. The WT800 would probably be the best match, as the early versions produced 400 watts per side into a 4 ohm load.

The later WT800C model(+/- 2006) put out 440 watts into a 4 ohm load.