Hi there,
I can happily report a successful unlocking of the bootloader as per
[root-dirtysanta-comes-for-the-h990] (http://forum.xda-developers.com/t/root-dirtysanta-comes-for-the-h990.3624296/)
followed by installation of /e/-0.16.
I had to downgrade stock from 20something to 10c first. Only thing in the process was that RUNMEFIRST.sh did not come up with a prompt . I had been waiting for 25min, the terminal on the phone came up with the prompt though. I simply opened another terminal tab (using Linux) and went on with step2. I flashed the latest version of twrp here.
Works all pretty well. Have some inconsistent GPS issues though and I wish the FM radio was supported by the kernel (there is apparently no custom ROM with a driver for the FM at all). Great that the quadDAC ist working though!
Cheers,
Fabian