Well this was an eye opener, another Poser 12 scene where I deleted all the lights and tried lighting the scene using Emissions from the light panels.  the snag was, even with some very long render times, white firefly issues was very strong.  Running the denoiser corrected that but the softening was so bad the faces on the figures not identifiable.

I played with the render settings but nothing seem to correct the problem until I loaded the High GPU preset and ticked Legacy Branched Path Tracing, increased the Adaptive Sampling w/threshold to 0.003.  There was a distinct improvement so, with Legacy Branched Path Tracing in use, I decided to try and drop the samples and finally finishing up with dropping the default from 25 to 5.  

This was the result after around 30 minutes, with no denoiser used, but I could have stopped it a lot earlier and all other render presets were looking like an overnight render.

 

 

I use Poser 13 on Windows 11 - For Scene set up I use a Geekcom A5 -  Ryzen 9 5900HX, with 64 gig ram and 3 TB  storage, mini PC with final rendering done on normal sized desktop using an AMD Ryzen Threadipper 1950X CPU, Corsair Hydro H100i CPU cooler, 3XS EVGA GTX 1080i SC with 11g Ram, 4 X 16gig Corsair DDR4 Ram and a Corsair RM 100 PSU .   The desktop is in a remote location with rendering done via Queue Manager which gives me a clearer desktop and quieter computer room.