Please post logs so we can see what’s going on.
It sounds like you’re describing something like compression or a limiter; loudness leveling inside Plexamp just increasing or decreases the volume on a track by a fixed amount. When using it there is a limiter included to avoid any clipping which can occur. If it’s engaged and you’ve turned the EQ “way up” you can cause this sort of clipping to occur.
If you’ve disabled loudness and the EQ, the loudness should be pristine and unaltered, and if you want things to be louder, turn up your stereo or car.
