It must be this? These are the only 2 identical PS in my studio that I don’t know what they go to and they seem to match the specs for the H9 — I thought they were left over from some other stuff I bought, since I have one of these MerryKing brand PS (different voltage and connector size) that came with a cheap Chinese computer accessory. Didn’t expect to see this brand to come with my H9s, but this must be it.

It says OUTPUT: 12V 500mA (center positive)

Mystery solved?