Hello Peter,
I was wondering how to output an ADM Mass in ET?
The easiest way is to use LSUThorns/QuasiLocalMeasures to compute the ADM mass either on a horizon (if this is what you want) or a surface far away.
It has some sample parameter files and I believe that the qc0-mclachlan.par file in repos/McLachlan/par also contains QuasiLocalMeasures.
Yours, Roland