I understand you're looking for an that works on Windows 8.1 (64-bit) .
Would you like a quick setup guide for Equalizer APO on Windows 8.1? equalizer for windows 8.1 64 bit
Since Windows 8.1 is no longer supported by Microsoft, some newer equalizer software may have dropped official support. However, many older or lightweight versions still work perfectly. I understand you're looking for an that works on Windows 8