Confusion about gears

[Sociopath]

i got a new plate dps shoulders from auriaya on heroic, best in slot so i took it over my t8 but the only problem was it would get rid of my 4 set bonus, since the t8 head gives ArP its useless for unholy dks, but i wonder if using the t8 head for the 4 set bonus along with the shoulders?

and yea i dont know how to link the items, im a nub at this

[Filed]

http://www.wowhead.com/?items&filter...0.94:0.93:0.03

Get some basic math on the go.