Thanks you for these recordings firage!
Yes, the CT2940 also rings but more faintly than the CT2890.
As I thought, the DMA clicking and Ringing problem are actually related and only happen with single-cycle DMA sounds.
The SB16 cards that click, do not ring.
The SB16 cards that ring, do not click.
It seems that residual ringing is heard because the DSP does not mute the signal and keeps the audio channel open.
The click is actually a closing of the channel as it should be, but it is not silent.
Now it is official, there is NO bug free SB16 and I'm not talking about MPU-401.
This is my personal opinion, if you don't need 16-bit sound in DOS games (hardly), I would stay away from the SB16 altogether, it is a really bad egg.
If you need 16bit sound in Windows 9x, there are MUCH better ISA cards than the SB16.
But if you must have one, I can say the CT2940 with YMF289 OPL is the most acceptable SB16 card if you find one.