On second inspection, I would like to add that you will probably need to think about how much sulfate compared to nitrate because
ammonium is 18.039 g/mol
nitrate is 62.004 g·mol
sulfate is 96.06 g·mol
ammonium nitrate is 80.043 g/mol
ammonium sulfate is 132.14 g/mol
HOWEVER - AS uses TWO ammonium molecules for 1 sulfate compared to AN which uses 1:1.
We see this in the formula for AS : (NH4)2-SO4 and AN : NH4NO3
We have twice as much ammonia in the sulfate salt compared to the nitrate salt., The nitrate weights less however. So you can see, we will need a molar equivalent per weight.
We wont have to worry about the solution being too acidic because of all the NaOH, and ammonia is basic also. At a quick glance, it seems to me that we would be able to use a little less than %50 as much AS compared to AN to produce the same amount of ammonia gas. I have not been able to find ammonium sulfate in any OTC consumer products however, so I have not experimented with this yet.