I'm unaware of any repair needed to a Musetec dac, at least to 005, may have seen issues with 004, but then that was major platform for diy mods and some bricked them.
@dbb I recall your comparison to Holo. One thing that's critical to evaluating R2R dacs that many don't account for is clocking. R2R resistor arrays extremely sensitive to timing errors. USB generally not going to be optimal input, I2S the way to go as clock runs on separate leg. And then in order to reach max potential clock clocking should generally be done in streamer or renderer. The Harmony is the hot dac of the moment (reason I chose it) and I've seen reviews from both complete novices and seasoned reviewers, I've yet to see what I'd consider to be optimal setup in these reviews. I'll eventually purchase either Musician Phoenix or Denafrips Gaia DDC, run this with Audioquest Diamond HDMI (level playing field with my usb cable of choice) and set Harmony to lock to clock in these high end converters. Harmony has been both dismissed and claimed to be state of art or near state of art by various reviewers. Based on these reviews can't say if this all hype or ignorance, I'll try to place it in context by optimizing the entire setup. Going in I don't expect a $2700 R2R dac to be state of art or even near state of art. the amount of technology in this dac is nice value, not state of art.
Going into comparison, I admit bias for Sabre chip dacs, I fully expect even 005 to exceed Harmony in resolving/transparency, 006 even higher expectation. My take on R2R going in is nice sense of musicality, but boring in long run, perhaps even short run. R2R dacs nice forgiving sources that hide warts, Sabre dacs expose warts elsewhere in system, high resolving sources require system fine tuning. This why some claim Sabre chip dacs not musical.