You asked about break-in of the Musetec DAC.
In his first post after receiving the Musetec, @pt999 compared it to his fully broken in May Holo KTE DAC. After one week of break-in he decided to return the unit. He preferred the May, apparently by a good margin.
In his second post, written after 16 days and 350 hours* of break-in he changed his mind and decided not to return it. He writes that, "The 2 DACs sound very similar. Switching back and forth multiple times on the same music passage, some the differences I found before are no longer valid. The Musetec air and space are about the same as the May." He continues to prefer the May saying the sound is a bit "crisper." That is usually more of a description of a sigma-delta DAC, but that’s what he says. He continues, "I’m not sure I can pass a blind listening test identifying which is which."
This very much confirms what @dbb has written as an OP after a full break-in of both units.** HIs break-in of the Musetec was longer than that of @pt999.
*Others have reported needing more time.
**Comparative Review: Musetec DAC and Holo Audio May DAC