TAS3251: Qusetion of analog and digital ground of TAS3251

Part Number: TAS3251

Hello~ 

I made a TAS3251 PCBA.

The  I2S input of TAS3251 is connected from another analog to I2S board.

But the output sound of TAS3251 is noisy.

When I power off, it will be normal before voltage drop to zero (about a second)

I use switch power supply, the Vin is 27V

Does TAS5251 need  to separate analog and digital ground ?

thanks.