DJM 450 headphone jack noise

Hello,

I've recently purchased a DJM-450 and noticed an issue: I can hear a costant noise through my headphones, when connected to the 3.5 mm headphone jack. The noise is noticeable, even when nothing is connected to the DJM and everything (including headphone volume) is turned all the way down or off. I'm guessing the noise is inherent to the headphone amplifier.

I've compared the DJM-450 to my DDJ-400 (connected to a Macbook Pro 2015 13 inch) and found that the noise level through the DDJ-400 headphone jack is considerably lower.

Is my DJM-450 faulty and should I send it back or is a certain noise level to be expected with the DJM-450 headphone jack?