Don't make additions of DAP alone. The DAP should be added at the same time as the Fermaid K in 1/3 portions as the wine ferments. For additional information, there is a good thread here
http://www.winemakingtalk.com/forum/showthread.php?t=39655
You may want to contact one of the Labs that supplies Fermaid and ask for a nutrient recommendation for a red must at 52 YAN. The following is what I've been doing for the past 6 years, and is based on the nutrient calculations provided by the BSG catalog.
https://bsgwine.com/Content/PDF/1.12.16_2016 BSG Wine Catalog PROOF.pdf
Most manufacturers publish nutrient addition rates based on 23 brix must with average nutrient deficiencies, maybe an initial YAN of 150ppm. Based on published information, a must at 23 brix may need around 200ppm YAN, but if the brix is 26 the required YAN is approximately 325ppm to 350ppm, even if you dilute the brix down, the required YAN is the same. Assuming you dilute to 24.5 brix, the final wine volume for calculation purposes is about 6.8 gallons. The additive packets of Fermaid contain 8g each, so you have 16g total. The 16g of Fermaid will provide approximately 62ppm YAN, and adding the 52ppm starting YAN gives 114ppm YAN, which is still too low. Subtracting the 114ppm from the 325ppm required means approximately 211ppm additional YAN needs to be added in the form of DAP. Therefore adding approximately 24g of DAP (~208ppm YAN) will provide the additional YAN. In highly nutrient deficient musts, if you try to add all of the required YAN with Fermaid or any complex nutrient, the wine flavor would be negatively impacted. The approximate addition schedule for three additions, inoculation, active fermentation, mid-fermentation before 10 brix, is below:
Fermaid 6.5g 6.5g 3.0g
DAP 6.5g 8.7g 8.7g
This topic is complex and there are many factors involved, there are no guarantees as even the pro's occasionally have trouble, all you can do is read the published information, take a stab, and hope for the best, and try to enjoy yourself along the way.