I've gathered together some instrument files for the XM Tracker format. These are fairly large, so I split them into multiple files. The source for them was the site "ftp.kiarchive.ru".

LocationSize (bytes)
CATEGORY-Instruments_By_Type--BASS-Basses.tar.gz33369398
CATEGORY-Instruments_By_Type--BELL-Bells.tar.gz2831387
CATEGORY-Instruments_By_Type--BRSWWIND-Brass_and_Woodwind.tar.gz32891834
CATEGORY-Instruments_By_Type--CHROM-Chrom_Percussion.tar.gz2324523
CATEGORY-Instruments_By_Type--ETHNIC-Ethnic_Instruments.tar.gz1278545
CATEGORY-Instruments_By_Type--GUITAR-Guitars.tar.gz28346379
CATEGORY-Instruments_By_Type--HITSTAB-Hits_and_Stabs.tar.gz9633185
CATEGORY-Instruments_By_Type--KEYBOARD-Keyboarded_Instruments.tar.gz40877915
CATEGORY-Instruments_By_Type--PERCUSS-Percussion_Instruments.tar.gz148803855
CATEGORY-Instruments_By_Type--STRINGS-Strings.tar.gz28963477
CATEGORY-Instruments_By_Type--SYNTH-Synthesized_Instruments.tar.gz84133926
CATEGORY-Instruments_By_Type--VOCAL-Vocal.tar.gz9998654
FX-Special_Sound_Effects.tar.gz50193806
GENRE-Instruments_By_Genre.tar.gz6541092
OTHER-Misc_files.tar.gz3671282