Finally my Adafruit VS1053 works in combination with Seeedstudio CAN shield, however:
you need the new library of Cory (mid.2015: CAN shield now runs on pin 9 standard)
new library of Adafruit from 2015, runs on CS=10
pin 9 (adafruit shield RST) goes to pin 5 for example
reserve pin 2 for CAN shield interrupts.
-paul-