Hello Doug,
If you use the mac DLS software synth or a GM/GS external synth to reproduce your midi files, the default channel assigned to drums is channel 10.
So you can either:
Change the drums channel in your loop files with
MidiKit:
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or insert the system exclusive message which assigns one or more other channels to the drum part:
Mixage Software
www.mixagesoftware.com
support@mixagesoftware.com