Huh? Turtle Beach Santa Cruz is actually a pretty decent sound card no matter what driver set you use.
I think the problem is more between the keyboard and the monitor than the drivers.
Seems like your observation and other online forum posts about TBSC and my computer consultant's recommendation of it are all in agreement and pretty much confirm what I've already suspected. Converting two channels to four really is a tradeoff regardless of sound cards and drivers that are used.
Thank you for your help.