How to make sound louder when record with asioout using NAudio?

Question

I have a trouble when recording audio file using asioout. When I playback file, the sound volume is too low. I hardly hear the sound. I cant raise output anymore than the current setting as the sound from loudspeaker will be much higher. Is there a way to make sound louder when recording file? I use interface audio (presonus studio 18|24) with microphone as input device.

This is my code when record file.

public void OnAudioAvailable(object sender, AsioAudioAvailableEventArgs e)
{
    if (Samples == null)
        Samples = new float[e.SamplesPerBuffer * e.InputBuffers.Length];
    e.GetAsInterleavedSamples(Samples);
    if (Writer != null)
        Writer.WriteSamples(Samples, 0, Samples.Length);
}

Answer 1

I've found a solution!. From this answer, I decide to use FFMpeg to increase volume of recorded file. Audio Volume Manipulation