TROUBLE: With AP525, I check the output signal. THD+N at high frequency（higher than 3K) is more than 0.8%, but it is only 0.08% wih the same level at 1KHz.
Cause to find:
1. check THD+N of the input I2S signal , it's only 0.03%.
2. check the output with no load, it's 0.5%.
3. check before the LC filter, it's 0.4%.
4. check without LC or load, it's 0.35%
Could you please tell me how to do next? Is there anything to check with the firmware?
Thank you.
