New update.
It's basically the same thing as the previous update, but it turned out that I hadn't configured it correctly. Plus, now it responds to the Loudness setting - if you set Loudness lower it has less effect.
I'm getting MUCH more bass now with very little distortion - at a cost though: The bass itself sounds bad if it gets really loud. But I think I can fix that in a later step. First I'm curious if this makes people happy

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The update can be found here:
Winamp plugin (DLL, save in C:\Program Files\Winamp\Plugins) :
http://www.stereotool.com/download/dsp_rt4.dll
Settings for more bass, copied from a previous post and slightly modified (!):
** HINT: Don't make all these changes at once. Each of these steps increases the bass level, continue only as far as needed.
Quote:
Change w.r.t. version 4.10: Loud bass now sounds out-of-tune, but does not distort highs anymore. Out-of-tune bass sounds should be less notable than distorted highs.
I'm getting good results using the following settings:
Start by selecting preset "FM Loud". Then make the following changes:
1. Loudness: Set "Allow louder lows" to 4000 (increases punch and overall bass level)
2. Multiband: Set the first 3 "down speed divider (decay)" sliders to .0001, .0002, .0003. (increases punch)
3. Multiband: Set the first 3 "soft limit" sliders to 7.29, 7.97, 7.63. (increases punch)
4: Pre Limiter: Set the bass band soft limit (top left slider) to 43.22. (increases overall bass level)
5. Multiband: Enable the equalizer, set the first 3 bands to 1.24, 1.24 and 1.12. (Make sure "Before multiband" is disabled) (increases overall bass level)