I am using Pure Path Studio to create a pass through program -- PDM input to I2S output. The ADC is set up with the MCLK at 4MHZ for a sample rate of 15.625 KHz. There is a 4x decimation block followed by an interprocessor block and ultimately into an 8x interpolator. The audio coming out of the I2S is at the correct sample rate but has a constant DC offset and has aliasing (eg. 9KHz sinusoidal stimulus is picked up as 7KHz). Any ideas what could be going wrong?