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I would suspect that the soft box which add probably 2stops to each flash, the extra distance added additional stops of light per the rule, and shooting in Ettl also added to the usage.
Say that you previously shot at 22 ft and use the flash at half power in manual mode to get the 170 pops.
Now your shooting at 30~ft which adds a stop of light that plus the 2 stops for the soft box adds 3 stops to you flash which means if the math is right you flash is at full power or close to it and don't for get the per flashes for the Ettl. I hop this make since and I'm not to far off the scale to make it simple using the rule for stops of light which has vacated my brain and I'm not going to research the name. It goes for a lens something like 2.8,4,5.6,8,11,16?,22,etc. you can you those same numbers as feet and for each incremental jump adds a stop of light which is just a jump to the next setting on the scale if thing change in multiple options if your using your Speedlights by itself ita full power call that one stop to properly light you subject and you increase the distance from 2.8 ft th 4 ft then you would need the same amount of light from a second sorce but you go to 5.6 ft then you'll need 3 more equal sources of light. I hope this helps explain what I'm try to convae