DDJ-1000SRT headphone hissing noise

I just received my second (replacement) 1000SRT which is having the exact same issue as the first one: I get a hissing noise on the headphone outputs. Depending on which headphones I use (HDJ-X10 or IEMs) the noise varies from annoying to unbearable for more than 20 seconds. Even if there is music playing the noise is audible.The noise is there even if nothing else is attached to the unit. It does not change volume as I turn the cue gain knob or any other knob for that matter. 

I complained about the first unit with my local service center and was told I should send it to the service center to get it fixed. As it was brand-new I refused and today got a replacement unit from my dealer. It has the exact same issue. I am not willing to get brand new 1500 bucks DOA units fixed the minute I unbox them. On-top it would take around 3-4 weeks, my dealer said. 

So - any hint would be appreciated as I am really lost what to do now...