Microsoft SysVAD (Virtual Audio Device Driver) micphone's sample rate is 48000Hz, how to change it?

I use one of the SYSVAD's virtual micphone: External Microphone Headphone.

And I remove the sine wave generator, read pcm data from a file (voice data recorded, e.g. input.pcm) and replace the original code in minwavertstream.cpp like below.

    //m_ToneGenerator.GenerateSine(m_pDmaBuffer + bufferOffset, runWrite);
    // by tomxue
    ReadVoiceBufferToDMABuffer(m_pDmaBuffer + bufferOffset, runWrite);

And I use Audacity software to record the voice comes from virtual mic.

I found that when the input.pcm is recorded under the conditions of 48000Hz/1 channel, the waveform recorded by Audacity has the best quality.

So my conclusion is that SYSVAD uses setting of 48000Hz/1 channel.

Now I need to change it to 16000Hz - 1 channel. I tried to modify the codes to replace 48000 to 16000, but did not work.

Could anyone please help to advise? Thank you!