ответили уже на форуме atariage:

It works under DOS in Altirra.
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Altirra's XEX loader resets POKEY after loading each segment so the segments near the end of the executable that write directly to POKEY are immediately counteracted:
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...
EXE: Loading program F3B2-17086 to 2000-9CD4
EXE: Loading program 1708B-1708B to D20F-D20F
EXE: Loading program 17090-17098 to D200-D208
EXE: Loading program 1709D-1709E to 02E0-02E1
EXE: Launching at 2000