In answer to your question, it does not appear that anyone named Denny Kress has ever been associated with the band Black Hawk in any official capacity.

There is no mention of a Denny, or Dennis, Kress or even a similar name whatsoever on the band's official website, located at http://www.blackhawklive.com. According to Wikipedia.org, the official membership of the band, past and present lists as follows:

"Members

Chris Anderson
Jon Coleman
Henry Paul
Michael Randall
Randy Threet
Monte Yoho

Former members

Anthony Crawford
Dave Robbins
Van Stephenson"

And a page devoted to the Blackhawk Band, posted here on Mahalo.com states the membership of the band as follows:

" 1. Chris Anderson
2. Jon Coleman
3. Henry Paul
4. Michael Randall
5. Randy Threet
6. Monte Yoho "

Furthermore, in a detailed retrospective of the band's history written by band-member Henry Paul, posted on http://henrypaul.com, there is no mention of a "Denny" or "Dennis Kress". Considering the length and detail of the history written by Mr. Paul, it is entirely plausible that had such a person been involved in the band at some point in its career, he would likely have been mentioned.

My research has led me to the conclusion that there has been no official involvement of anyone by the name of Denny Kress in the band Blackhawk, officially, at any rate. A list of the names of all sound-technicians and stage-crew employed by the bands does not appear to be in evidence on the web at this time, though one cannot rule out for certain that Mr. Kress did not at some point have some involvement with the band in some unofficial capacity. However, such data remains non-existent, so far, in public record, so the official answer is "no".