Did you ever hear back from them on this? Mine cracks between tracks when the sample rate changes. It also cracks when paused. The crack seems to hit my tweeters at max volume.OK, got some news.
I send email to Hidizs to tell 'em about this "clicks" and "rings" problems, and 1 day later i got an answer!
They asked me if i can record the sound where they can hear this noises. Of course, i can, being a recording engineer )
So i did, and sent audio to Hidizs, now waiting for their answer on a problem.