Note, pin 11 is MOSI, and pin 12 is MISO by default.
PJRC just released a revision D of the Audio Shield that works with the Teensy 4.0 (but not the T3.6 without using jumper wires). On the Teensy 4.0, the SPI pins are back to 11-13, and the I2S (sound) pins are 23, 21, 20,7, and 8. So in theory, the T4, the new T4 audio shield, and the XP2046 should all work together without any jumper wires.
For the T3.6 using the revision A-C shields, you have to use the alternate pins for SPI. I would imagine with the XP2046, you just need to use jumper wires to connect pin 7 on the Teensy 3.6 to the MOSI port on the XP2046. You would need to use the
SPI.SetMosi function to change to use the alternate MOSI pin on the T3.6 to support using pin 7 instead.
Earlier I posted about connecting a Teensy 4.0 to a revision A/B/C Audio board and what jumper wires you need to do. As I said there, it was found that the Teensy 4.0 requires the MCLK signal to have a 100 ohm resistor wired in series (revision C board adds this wire):