After a lot of trying a managed to insert stereotool as a command line in the transcoding chain and it is working perfect. See this post if tou are interested
http://forums.stereotool.com/viewtopic.php?f=4&t=3679
Stereotool is much like soundsolution, maybe better, and free. Give it a try, first in winamp or as a VST, cause it seems a bit difficult at the beggining. Start from a preset.
Meanwhile, I guess the insert function of any DSP or VST will have to wait, allthough it would be awesome to have the possibility to insert an effect chainer, like Acon's one.