Updated from the old one to version 1.01, it is a 3 in 1 channel polarity inverter, no longer limited to both channels, you simply pick inverter for channel 0, 1 or both 0 & 1 from the DSP manager.
Simple Polarity Inverter v1.01 for foobar2000 v0.9.x (file size 46.02 KB)Hope you like it.
The zip file appears to be damaged. (At least that’s what Winzip claims after I downloaded it, twice. Ditto 7-Zip and WinRAR)
I have just checked (downloaded it) and the file is fine.