UnitedPlugins has discounted DIFIX by 50%, $29 instead of $58, until May 28th, 2021.
A lot of sound cards claim to have a Hi-Z instrument input. But in reality, the input impedance is not high enough to make your pick-ups work properly. And that has a displeasing effect on your instrument's signal. If you use one of these types of soundcards, you definitely need DIFIX to make your directly recorded guitars or bass sound right.