I would recommend trying the regular Sound Blaster 16 (sb16). Windows 98 should already have the files to enable plug-and-play installation.
If that, in conjunction with increasing the block size and prebuffer, makes no difference, then the issue you are experiencing is more likely to be related to underlying performance issues. If “max” cycles is already set, experiment with how high you can set fixed cycles and still achieve usable performance. For example:
cycles = fixed 120000
DOSBox SVN for macOS (x86-64) - customized with Munt MT-32, Nuked OPL3, 3dfx Voodoo, Extra RAM, Large HD, and more.
https://github.com/almeath/DOSBox-SVN-64-bit-for-macOS