Yet another source plugin suggestion:

[dimzon]

Read this post:
http://forum.doom9.org/showthread.php?p=777465#post777465

[tateu]

Are you looking for a plugin using that specific winamp dll or just something generic that will open aac?

If you are looking for something generic, a new version of my quicktime plugin (that I have not released yet) can open quicktime 7 compatible aac files. I don't recommend it as a permanent option, because, well...it was programmed by me, but until something better comes along...

Also, it is quicktime after all, so I'd have to imagine that it's decoder might be limited to a subset of the aac format.

It'll probably be a few days before I get it cleaned up and released.

[Revgen]

You can use Winamp DSP plugins through ffavisynth. FFDshow's audio filter can use Winamp plugins. Just set up FFdshow to use the Winamp audio plugin you want and then use this script.

LoadCPlugin("yourdrive:\ffavisynth.dll")
ffdshow("default")

The othe non-DSP plugins can't be used though.