I have a jack wired from my radio wire. I can only put about an 80W load on it before the inverter protests.
I also have a jack wired at the 12V panel. I have run up to 300W on this one with no problems.
I have tried three different inverters on both jacks - the results are always the same. I have tried running the radio wired jack with no other 12V draws in the RV - the inverter still protests (loudly) over about 80W, even when plugged in to shore power. My conclusion is the wire to the radio is too small for a larger load. Yours may be different.