Two 802 for a 75 gal seems too much, unless power is set to minimize (but then whats the purpose of having 2?). Whats the powerhead set up for? Water disruption/oxygen mix, filter, waterflow..??? I seriously think that a combination of 1 Emperor and 1 802, 2 Emperor, or even 2 Emperor with 1 802 minimized power would all work.
BTW: With all those filters producing too much oxygen mixture in the water, it can also produce problems with your fish down the line. (I forgot what it was called, but on the tip of my tounge).