ADAU 1452 distortion and EQ frecuency error

Hi, I'm building a project using a raspberry pi based streamer using volumio and a I2S DAC,

the first prototype was only the respberry pi and the DAC and it worked fine, the sound quality was excellent.

I read about ADAU1452 and I decided to buy a learning board using ths chip in order to add EQ capabilities and add 2 more inputs to the DAC ( i2s USB module and i2s ADC)

After a time I managed to build a prototipe but I'm having problems and I need help.

1. The main problem is about sound quality for exaple, when I add a EQ band at 500hz and 5db of gain and then I use REW and make a measurement of the frecuency responce the result is strange, it seems that the effect of the boost is far ahead in the frecuency range, In order to make a boost of 5db in the fracuenci range of 15,000hz to 20,000hz I have to add a band in the 700 hz range and if I need to add a EQ band in the 40hz it is imposible.

2.If I turn the volume up I can hear distortion and the qualyty is realy bad

Thanks for your time