Danthewizard

I'm having a very similar issue. When I try to use my Toneport UX2 with Logic Pro X or Garageband on Mavericks I'm getting random pops/clicks which disturb the recording. It is really bad when on the lower buffer settings, but still persists even when on the highest, often ruining some good recordings! Like you say, this didn't happen on my old Macbook. I phoned Apple Support and they told me it was more than likely a driver / compatibility issue between the Line 6 device and Mavericks...