DDJ 800 - Microphone channel Noise

Hello. Since i bought ddj 800 i got a lot of noise from microphone channel, even while my microphone is not plugged in. It depends on gain value but even with normal volume it can be heared on speakers and headphones. I recorded that noise -> https://files.fm/f/5vqmpt5w4

From the begining channel is OFF, after i put ON microphone Channel and in next step i started raise the volume -> in all cases microphone is not plugged in inside. 

I also noticed that light from microphone channel (red one) gives light with little pulsation. 

In my conclusion there is something wrong with power supply so i was looking for solution. I found filter which reduce all noises but i am afraid to use it before consultation - > https://www.palmer-germany.com/en/products/power-supplies-chargers/5235/purifier

Maybe im wrong but still i need answer coz it gives me no peace at all.

ps. I forgot to say that i checked the problem with pc plugged in (via USB) and standalone. Results were same sadly.