if that logic is sound then what if I wanted to cover the 1 sqft with an array of 9 cobs running 180ma or lower.
So basicly whats the lowest amps I could use and if I am talking crazy how could I try to reduce the existing 25-35w per sqft usage during flowering. Is it possible to get it closer to 15-20w.
Yes it would be possible to run a lot lower than 35W/ft² if we crank the efficiency, and the method you described would definitely do that along with better coverage and less light lost to scatter. There are
cheap 300mA drivers that are 89% efficient with 150V max Vf. There are 120, 150 and 180mA drivers that can do 88% efficiency very cheaply. Or you could use a Mean Well HLG-185H-C350 and run a long string dimmed down to as low as 35mA.
The downside though, increased complexity of the build, increased up front cost and I suspect less "reach" into the canopy. For example, at 1400mA, the CXA3070 AB cost about $1.86/PAR W, at 700mA it is $3.40, at 350mA $6.46, at 300mA, $7.41. That is as low as my data goes, but I estimate that at 150mA it is about $15/PAR W and 62% efficient, 5W each (
200lm/W).
The CXA3590 3000K CB bin could take that idea even further, maybe to 65% at 100mA (6.5W) for $15/PAR W.
Rather than experiment at that level in the flower room I have been experimenting in the veg room, running CXA3590 5000K at 280mA, or about 63% efficient. I plan to try running them passive cooled at 200mA or 67% efficient (
217lm/W). It will be dimmable from 35mA to 350mA. No practical reason to do it, just curiosity and extra parts to play with. So far it is working very well but I would like to see what they are really capable of at $15/PAR W. I guess that would be very useful to keep your ladies in veg mode during an extended power outage or in a solar powered grow.
i can't find anywhere in his listing part number where it says Z4 or AB 
Happy new year to you sir 