By looking behind the h9000 it has only 2 outputs, XLR analog connectors:

https://tacsystem.jp/products/eventide/h9000

There are 8 channels of analog IO on the two Dsub connectors labeled "ANALOG 1-8" on the diagram.  The first two channels are the same as the XLR connectors.  You need break out cables for the Dsub connectors to connect to other equipment.  Then you could use the XLRs for the Magni 3 and channels 3-8 on the breakout cables for your other analog equipment.

If you need further help with your setup, please email support@eventide.com and we can give you more information.

Also, do I lose sound quality by using a device that is inbalanced? (Magni 3 has unbalanceds) or this only matters if I need very long cable?

Balanced is always better, but it should still work well with an unbalanced connection.