xapofx1_5.dll
This file belongs to DirectX End-User Runtime. Install that package and the DLL arrives with it, in the right place and correctly registered.
Do not download this DLL on its own
Searching for a missing DLL by name leads to sites that hand you that single file. It is one of the oldest and most effective malware delivery methods there is, and a system DLL from an unknown source is indistinguishable from a deliberately modified one. There is never a legitimate reason to obtain a runtime component that way.
What it is
The XAPO audio effects library from the legacy DirectX set, used for reverb and filtering in older game audio engines.
Where you see it: Games from the DirectX 9 and 10 era with positional or processed audio.
Install DirectX End-User Runtime
The official package, with the download URL Microsoft declares and the SHA-256 of every installer so you can verify it before running.
After downloading you can check the file against our index to confirm it is the installer the publisher shipped.