Nine-input sorting network of optimal depth with minimum number of comparators
I found a 2002 Reference of the Best-Known Sorting Networks for up to 16 Inputs by Ron Zeno including a diagram of a 9-input network that seems to fit the bill.

His nine-input sorting network of depth seven uses the following arrangement of comparators

{0, 7}, {1, 6}, {2, 5}, {3, 4},
{0, 3}, {1, 2}, {4, 7}, {6, 8},
{0, 1}, {2, 6}, {3, 4}, {5, 8},
{1, 2}, {3, 5}, {4, 6}, {7, 8},
{1, 3}, {2, 4}, {5, 7},
{0, 1}, {2, 3}, {4, 5}, {6, 7},
{3, 4}, {5, 6}  



Wolfram demonstrations includes a beta about Sorting Networks, which in due course contains an example of an optimal (module count) nine-input network:


  {{1, 2}, {4, 5}, {7, 8}},
  {{2, 3}, {5, 6}, {8, 9}},
  {{1, 2}, {4, 5}, {7, 8}, {3, 6}},
  {{1, 4}, {2, 5}, {6, 9}},
  {{4, 7}, {5, 8}, {3, 6}},
  {{1, 4}, {2, 5}, {6, 8}, {3, 7}},
  {{2, 4}, {5, 7}},
  {{3, 5}, {6, 7}},
  {{3, 4}}  


(That's probably about as close as I will get to providing a visualisation:
looks trivial to plug "the Flensburg" or above 7-level configurations.)