There are fundamental issues with accessing the SD card from your foreground code at the same time as using AudioPlaySdRaw, because the latter accesses the card from the Audio update interrupt. Sooner or later one access will interrupt the other...
i everyone,
I’m building a simple looper on Teensy 4.1 + Audio Shield, using BUILTIN_SDCARD with the Teensy Audio Library:
AudioInputI2S (guitar on line-in)
AudioEffectFreeverb for monitoring only
AudioRecordQueue for recording
AudioPlaySdRaw...