So I've been using my CTH + SDAC for a couple years with no problems. However, within the last month or so, I've been running into a few issues: some hissing in the right channel (which is only really audible at 0 volume) and sometimes there are clicking sounds from the box during which the sound cuts out. It seems like it's struggling to stay fully active for some reason. I just bought a replacement 6922 tube to see if that would fix the issue. It seems to have solved the hissing, but there's still intermittent clicks that cut the audio. It's the same clicking sound that happens when the unit's LED changes from red to white and allows audio through during normal operation, but it will happen repeatedly and quickly in succession, without the LED changing, and the audio will go in and out. Has anyone had this issue or know what's going on?