VXD is the driver of choice for this era of machines due to the higher performance and better support for sound in 16-bit applications and the guides focus on this driverset. It's possible that the shortcut install method used doesn't result in functioning WDM drivers, I only ever used the retail install CD for WDM and the shortcut/easy method for VXD. The issues you are having don't seem to be VXD specific either as people don't report crackling or repeated sounds as a normal experience.
My guess is whatever was messing with the graphics card, is now doing the same thing to the sound card.
98/DOS Rig: BabyAT AladdinV, K6-2+/550, V3 2000, 128MB PC100, 20GB HDD, 128GB SD2IDE, SB Live!, SB16-SCSI, PicoGUS, WP32 McCake, iNFRA CD, ZIP100
XP Rig: Lian Li PC-10 ATX, Gigabyte X38-DQ6, Core2Duo E6850, ATi HD5870, 2GB DDR2, 2TB HDD, X-Fi XtremeGamer