The CS-4236 is an excellent DOS soundcard. It has a very good SNR, high compatibility and no hanging note bug on it's MPU-401. The only possible negative is that the FM synthesizer built into it does sound different from the Yamaha OPL3, however this is personal preference whether it sounds bad or not. Audio quality and noise will naturally be determined by the analogue stage of the motherboard. If it's been well designed, the sound quality will be excellent and noise levels very low.
My two favourite games for testing the sound quality of the SB-Pro part is Epic Pinball and Dune 2. Epic Pinball will quickly reveal if the sound channels are swapped and if the soundcard has a poor anti-aliasing filter. The music will be scratchy and have a "ringing" sound to it if the anti-aliasing filter is badly designed and if the channels are swapped, pressing the left shift key will play the flipper sound on the right channel and vice-versa. (Obviously choose SB-Pro as the soundcard in the setup menu)
Dune 2 is also a good test for the anti-aliasing filter, it also has a "ringing" sound to the voice if the anti-aliasing filter is badly designed.I remember being gob-smacked at how good it sounded on the Turtle Beach Tropez+ soundcard when I heard it the first time. The Tropez+ soundcard has the CS-4232 chipset which is the same as the CS-4236, just without the built in FM Synthesizer, however, it has one of the best analogue stages of the ISA consumer soundcards out there.
Sorry Kisai, but saying that avoiding all soundcards that are not Creative Labs soundcards is utter nonsense. There are many other excellent cards out there that are as good or better than the Creative Labs ones, Aztech, ESS based, YMF-71x based and CS-423x based are a few that come to mind. Many SB clone and genuine SB cards suffer from poor analogue design though and are noisy, have poor frequency response or pick up digital or power supply noise from the motherboard or other expansion cards in the PC.
Gerwin has a few posts on the CS-423x chipset, look them up for a better understanding of the chipset and driver downloads for it.