I am somewhat relieved to hear that my GH5's Microphone Input is likely not damaged, but I don't have a Mic with 1/8" cable with which to test it.
The GH5's documentation is seriously lacking details on the Mic Input, but Panasonic sells an optional DMW-XLR1 audio device for the GH5 that provides 48V Phantom power, so I do not believe the built-in Mic Input of the GH5 offers such phantom power output. (And if you're wondering, I am not interested in buying the $400 DMW-XLR1 because it is bulky and mainly targeting people who want to use XLR Mics, which I do not.)
I don't see how I can effectively use an L-Pad Calculator because, again, I don't know the LOAD IMPEDANCE (which in this case is the GH5's Mic Input). Remember, I know the spec only of my D100's Line Output:
• Output impedance: 220Ω
• Rated output level: 1.7 V
• Recommended load impedance: 22kΩ
• Output level: –21dBm to –15dBm
The GH5's manual does not give any specifications of the GH5's built-in Microphone Input. It's probably something low like 680Ω, but that is just a wild guess. (If it was high like 22kΩ then my D100's Line Output shouldn't clip when fed into that Mic Input.) So what do you suggest in light of this?
Furthermore, you mention capacitors to remove DC, but from what I see a lot of L-Pad "Line Level to Mic Level" attenuation cables simply have the dual voltage divider resistors. I don't see that they have the caps inside. A previous poster suggest I use a D.I. box, but those are just as big and bulky as the $400 Panasonic DMW-XLR1 box. If I can solve the problem with a short cable (with needed circuitry built-in) that would be the best overall solution.
Further thoughts in light of this would be greatly appreciated.
Thank you.