AudioOutputI2S_F32 2-channel emits buzzing noise with no input

[Greg-R]

I've been developing a 4-output I2S F32 class and in the process I did a lot of testing of the 2-output class.
I've forked the repository and created this example:

https://github.com/Greg-R/OpenAudio_ArduinoLibrary/tree/quad_i2s_output/examples/AudioOutputI2S_F32_Example

The sketch drives the I2S 2-output with sinusoidal tones from the F32 library. The tones are turned on and off.
You can listen to the tones by plugging headphones into the Audio Adapter.
The problem is that when both tones are off, there is an obnoxious buzzing noise from the headphones.

I think the problem is that somewhere in the code the audio block memory is not being released.
So when the tones are off, the memory blocks are still being played, but they are not being properly interleaved,
resulting in the obnoxious buzz. That's an unverified theory.

The quad output class that I derived from this class and the I16 quad output does not have this problem.

Another possible issue with the dual output is that it does not memset the data buffer to zeros when it is initialized.

Regards,
Greg