My German is very poor, but I couldn't to ignore it.
Yes, C1084 can display CGA, of course digital TTL. 8-pin DIN is ok.
But WARNING here: If you replace videocard to EGA never, really never power-on with connected C1084 powered-on!
EGA allows to inverse sync - and this KILLS your C1084, even near all Commodore monitors not capable to handle inverse sync.
I'm 128er and C128 VDC version 8568 (DCR version) allows to use it and can produce 16 color EGA - but this mode is on all Commodore monitors their DEATH.
VDC 8563 used in C128 and C128D has not this feature 'cause it has not 38th register of 8568.
I used EGA mode on C128 only by converters CGA to VGA or others with turned off C1084.
So, have it in mind when/if you change videocard to EGA.