Hello!
I looked a little bit deep into it, and find as expected a small bug, which had unfortunately big impact and brings this strange behaviour @
giaur mentioned. In fact add-on is doing its job but there is a problem of saving parameters. Here we go!
First I deleted parametricEQSettings.xml from userdata/addon_data/adsp.biquad.filters, started a song then I set EQ parametes as follows:
Preamp 1db
32 Hz 2 db
64 Hz 3 db
125 Hz 4 db
....
8 kHz 10 db
16 kHz 11 db
All good for now, addon working.
Then press OK saving parameters, this mean generating new parametricEQSettings.xml file, looked into it and get next result:
</settings_group>
<settings_group sub_category="gain_10_bands" group_name="front right">
<setting key="gain_32Hz" float="1" />
<setting key="gain_64Hz" float="2" />
<setting key="gain_125Hz" float="3" />
<setting key="gain_250Hz" float="4" />
<setting key="gain_500Hz" float="5" />
<setting key="gain_1kHz" float="6" />
<setting key="gain_2kHz" float="7" />
<setting key="gain_4kHz" float="8" />
<setting key="gain_8kHz" float="9" />
<setting key="gain_16kHz" float="10" />
<setting key="gain_post" float="11" />
If you compare settings with saved parameters you get it.. 32 Hz value is 1 instead of 2, 64 Hz is 2 instead of 3, ... 16 kHz is 10 instead of 11, and gain_post which is preamp I think should be 1 instead of 11. This mean that each value is shifted one position. This also mean that at next song you do not get what you expect..
So I hope this info is helpfull and I'm sure @wisler will fix it, because is minor issue and this add-on is really amazing.