Druck von Emil Streisand published academic dissertations
I googled "druck emil paechter" to learn more about our ancestor's printing business in Berlin. I got all sorts of wonderful hits for academic dissertations published by Druck von Emil Streisand in the 1890s and 1900s. You'll remember that Streisand was the family name of Paechter's wife.
The publications are mainly legal or medical doctoral dissertations published for defense at a variety of German universities. It seems this was the main business of Druck von Emil Streisand. However, there is also a somewhat disturbing patriotic poster published in 1914, at the outset of WWI, that sums up German Jewish support for the war effort.
The headline reads "German War Surprise—1914" and depicts German military victories in its Belguim campaign that were aided by use of the 42-cm field artillery cannon popularly known as Big Bertha.
"With God, for King and Fatherland" is the slogan printed at bottom.
Since many of the dissertation publications date to the 1890s and Emil did not marry Helene Streisand until 1906, I was at first revising my timeline for Emil's arrival in Berlin. But then I checked and now see that Emil Streisand was the name of Helene's father, and thus that the publishing company belonged to the father.
My earlier conclusion that Emil was brought into the business after he married Helene now seems to be supported by the evidence.