First I'm sorry I react so late but I was away for a while.
Well, very great feature there. Wonder where you got that neat idea...
However, I have two things to mention :
1) Not really pertinent but anyway it might help to solve what is for me a mystery : I think it would be better to have a third colour (like rose) for the OSD power LED, so that it can really emulates the thing. Don't know if this would be easy enough to do and worthy. But the real question beyond this is : why doesn't the power LED (OSD or even lower bar in windowed mode) remain all the time ? Under Workbench or the loading of games it's on but then it's off (and it happily flashes when WinUAE has the premonition the guru is about to meditate). Could this mean the sound filter is on during the loading of games and under Workbench and switches off when calls to the sound chip are made ?
2) More important : The power LED sound filter effect emulation worked for Dune (F3 key to activate/deactivate the sound filter. You have to press another key before pressing F3 again and having the filter state changed). But it didn't in Lotus II (Second level, under the tunnnels. PW for the level : Twilight). I can only see two reasons : a) Lotus II uses another sound filter. Seems a bit illogical. b) The game makes temporary calls to the filter and Winuae can't catch theses calls, thus the lack of emulation.
In fact, after a few tests I've just seen that using F3 in Dune already affected the power LED in WinUAE 0.8.22 Release 5 (haven't check older revisions), so I wonder wether I really got the idea of the sound "power led" filter emulation.
As a conclusion, I have no conclusion, I don't understand anything, the Amiga still remains a mysterious machine. All this stuff is minor compared to other features I reckon, but it's still one step towards perfect emulation.