Raczej nic nie trzeba przerabiac w ptplayerze wersja 6.4.
Dziala i na timerze i na VBI.
Dla odgrywania 50 Hz muzyki na 60 Hz VBI,  mozesz uzyc czegos takiego w procedurze VBI
  
VBI
  move.b NTSC,D0
  beq.b Play
  addq.b #1,Counter
  cmp.b #6,Counter
  bne.b Play
  clr.b Counter
  bra.b skipPlay
Play
  bsr.w PlayMusic
skipPlay
  rts
NTSC
  dc.b 0
Counter 
  dc.b 0
link
To sa 2 opcje do wyboru:
d) Setting NO_TIMERS=1 disables the use of both CIA-B timers completely,
   which means that the player doesn't depend on level-6 EXTER interrupts
   anymore. NO_TIMERS=1 automatically includes VBLANK_MUSIC=1 (see below).
   With NO_TIMERS set, your main program has to call all music subroutines
   itself. The typical procedure in a VERTB-based main loop would be:
   1. call _mt_music
   2. wait at least 550 ticks, then call _mt_dmaon
   3. wait at least 550 ticks again, then call _mt_setrep
   The last two steps could for example be done by Copper interrupts.
   CAUTION: You should know what you do, if you use this mode! It is up
   to you to take care that calling a ptplayer function is not interrupted
   by another ptplayer function.
e) Define VBLANK_MUSIC=1 (defaults to 0) if you don't want ptplayer
   to set up a CIA-B Timer-A interrupt for music replay, which means
   you cannot set the tempo with the F-command anymore (only the speed)
   and you have to call _mt_music yourself out of your own VBlank
   interrupt handler. Also sound effects will no longer work, when no
   music is playing.
   NOTE: CIA-B Timer-B is still used for enabling Audio DMA and setting
   the loop pointers (unless you define NO_TIMERS=1). So it doesn't free
   the Level-6 interrupt vector. This is just an option if you must
   synchronize your music with your game or demo running in VBlank interrupts