By slip-feature I can now, among other things connect SSD disks and simultaneously use the monitor.
The monitor is connected via Thunderbolt - VGA Adpter. VGA only because about Thunderbolt - DVI adapter and DVI - HDMI cable comic colors are displayed.
But that is on my monitor to other monitors it also works over DVI.
FIX: Using a "Thunderbolt - HDMI adapter" It now also works on the monitor and the image is again digitally and especially sharp.
With a good SSD to reach write speeds of 360 MB / s and read speeds of 380 MB / s
If the monitor is connected but I can not connect additional Thunderbolt devices.
You'd need an adapter with 3 Thunderbolt ports that would be perfect.
The only downside is that the plates are free.
With old 3.5 disks I would be extremely careful that are not really sure on that thing.
But overall a great solution!