Playing *.MID/MIDI files changes my 64-bit W7 HPE SP1's volume mixer's Winamp.

[ant]

Every time, my Winamp v5.666 plays an old school *.MID/MIDI file, my decade old 64-bit W7 HPE SP1's volume mixer lowers Winamp's audio volume. How can I tell it not to do that? Changing settings in Winamp's Nullsoft MIDI Player v3.55 (in_midi.dll)'s Device's Volume Control doesn't seem to help. I don't have this issue with other audio formats (MP3, OGG, XM, IT, S3M, 669, etc.).

Thank you for reading and hopefully answering soon.