MCD1100 DAC - Annoying Noise Between Songs

[SAPHANA]

I have multiple DAC units, the DAC in MCD1100 is my second favorite (PS Audio DSD is my favorite BTW). However, there is an annoying problem which has been bothering me.

I use Mac Mini to feed music from Roon to this DAC through USB. The issue happens in every single gap between songs: a faint whistle like sound (~half second).

In the beginning I thought it was one of the common issues when a DAC switches sample rates, so I changed setting in Roon to mute for a second when the "switching" happens, but it did not help. Then I realized the noise does not come from speakers. It's from the inside of MCD1100 instead!!!

The noise sounds like something a CD player gives when a CD is just inserted. To me, it's more "mechanical" rather than "digital". It's very low in volume but still sensible.

Any ideas?