I’ve seen intermodulation distortion issues in both analog and digital gear. Poor designs don’t seem to discriminate between analog or digital implementation. If you test with your analyzer using 19 and 20 kHz and there is significant difference product at 1 kHz it’s likely to add a fuzz or harshness. But if the first order difference product is fairly low in level and what’s left is just some extra stuff created in the high frequency region, the IM can be fairly innocuous.
If you see lots of additional products in the midband other than 1 kHz, it is likely due to aliasing and that can cause harshness and fuzziness. I’ve seen that in a lot of analog-emulation plugins — and I don’t like its sound one bit.
Keep in mind that if the device produces some “good” harmonic distortion, particularly second and third, and this is dominant, with relatively little stuff above 3rd harmonic, then the device’s residual IM may not be audibly significant.
Also remember: If it sounds good, even if it measures bad, it is good!