AK4497eq has two types of output ?

As you can see in the datasheet, page 11, the HLOAD makes it possible to drive a much lower resistance. You can activate it either by setting the HLOAD bit to 1 (in Register Control Mode) or setting the HLOAD pin (pin 15) high (in Pin Control Mode).

I tested the HLOAD option once. I found the distortion was lower when setting HLOAD to 1. At 1 kHz, -20 dBFS it went from -124.2 dB THD to -129.2 dB THD.