Just to make sure I didn't confused myself. This is iDAP-6 thread but you are talking about the relay click sound in iDAC-6MK2 and want to replace the IDAC-6MK2 with a new unit, hoping that the click sound will resolved? For your information, there is a
iDAC-6 thread and most of the iDAC-6MK2 discussion were raised in that thread.
The problem won't solve with a new unit. Whenever iDAC-6MK2 detected a pause in the bitstream, it will assume the next audio signal might be a different sampling frequency, so the mute relay will kick in and wait for the "pop", and will unmute just before the music start. The TV signal is appeared as one continuous bitstream that's why the mute relay does not comes in. Change to another unit of iDAC-6MK2 will not solve this problem, it will still detect the pause and you'll still hear the click relay.
One thing you can try is to enable gapless playback in your iDAP-6, this feature is in the Music Setting menu. This might reduce the frequency of the "pause" detection between tracks, but this won't solve the problem completely, Some album has inserted a longer pause between tracks, or if you have manually inserted a pause between tracks when you rip a CD, these can't be removed by Gapless playback. If you have copied music files from different album into one folder, most likely the gapless function will not remove the pause as well because the metadata are completely different among tracks.