I agree with bonaventura that it is unlikely that you have an impedance problem (although, saying that the that the clarus "tolerates" a minimum impedance of 2 ohms rather than saying it "requires" 2 ohms would avoid potential confusion).
I'm assuming that you are still using the realist as you state in your profile. I suspect that you've already checked these, but, just in case...
I found the realist was really good at low volumes. But, as the volume increased, the pickup got "muddy" and prone to low-frequency feedback. I had to aggressively adjust the bass and mid-range tone controls to compensate (don't forget the shelving control). This seems to be a common experience for realist users.
As for the distortion, is the bridge is sitting upright? If the bridge isn't sitting flat down on the realist, it can distortion; although, that's usually reported as a "buzzing" sound rather than distortion per say.
Assuming that you still have problems, I suggest that you will get more helpful comments if you can describe the frequency at which the feedback occurs.
