Eero Aro noted that Reaper will open "AUD" files. Know that the 
developers of Reaper were the developers of Winamp.

IMHO, Reaper is an amazing DAW at an amazing price. Go to their website 
and download the software. It's the full featured version that is 
nagware for 60 days unless you pop for the $60.00 license (Yes, I said 
60 bucks for a full featured DAW). At the end of 60 days, the free 
version will end unless you buy it.



Corey Bailey Audio Engineering

On 2/28/2018 12:20 AM, Eli Bildirici wrote:
> An AUD decoder used to be part of Winamp's built in waveform plugin, but it was removed. However, there are custom plug-ins that can play AUD in their native form as well as programs to convert AUD into uncompressed WAV."