Klark Teknik pre DN 27A

Hi
some weeks ago i did ask for a schemo about the DN27s and someone could give me a little help... thanks for that, Milos. ;-)
But now there is a serious problem on reconstructing the EQs.
On the PCB of one of them are two bigger, black boxes. First of all i thought thats are relays (looks like a relay case).
On the second look i realized, that this small boxes must be a pre -
amp or so. I opened the black cover and found a cast in circuit that i cant
reconstruct.
Unfortunately the second EQ hasnt got this anymore... dismatled.
Thats where the problems starts.

Is anyone in this forum who can tell me, what i have to take instead of
this small preamps or whatever it is. Otherwise i cant reconstruct the
pre - DN27A (keep in mind, thats are PRE DN27A, if necessary i can post a picture of them. They have got only the Label "TEKNIK - 27s" on the Front Panel).
Thanks for helping.
Henry

Here is a link to the Klark Technik site:
http://www.klarkteknik.com/operators_manuals.htm
but it doesn't mention your unit.
Stephen