Thanks PT, but it does not clarify the situation IMO. Perhaps others with Magnums can step in here.
"15a shore power" can mean all sorts of actual amounts at the time and for how long. It does not define "15a input" to the Magnum.
If the Magnum trips doing 127DC amps output because it is only rated for 125, that is just weird. Most converters rated at 55 amps eg, will do about 60 amps if the converter-battery wiring is fat enough and the 120v input stays around 120v and does not drop off so you get less Dc output. My 100 amper does 103 or so the way I have it. Might do more, don't know.
Time2roll was getting similar higher amps with his 55 WFCO around 60 amps ISTR. We need actual measurements for the Magnum settings.