DFARS 219.201 basically states that the small business specialist must review and make recommendations for all acquisitions over $10,000, except those under the SAT ($150,000) that are totally set-aside for small businesses.  DFARS PGI 219.201 states that agencies are not precluded from requiring actions over $10,000, but under $150,000 that are totally set-aside for SB, be reviewed by the small business specialist. 

You have a sole source under the SAT.  Technically, it is not a set-aside as a set-aside is the reserving of an acquisition exclusively for participation by small business concerns (FAR 19.501(a)). Notice that the word "concerns" in the previous sentence is plural.  FAR 19.502-2 (a) also describes a set-aside under the SAT as having an expectation of obtaining offers from 2 or more small businesses.  You have one offeror as it is a sole source, so therefore a DD Form 2579 is required.  You will still want to discuss this with your small business specialist, as they may also require a DD Form 2579 for all requirements over $10,000 (PGI 219.201) whether set-aside or not.