+1 @lordmelton
Break in period can be "interesting" to say the least. My tube amp was so bad at time I just had to leave the room cause I couldn't stand the sound. I would think the Dac would be as bad but it will be noticeable.
OTOH, it "might be changing filters", as @mahler123 suggests. Problems with new electronics tend to show themselves in the 1st 3 months IME.