Pioneer DDJ-RB sound from monitor studio crackling PROBLEM

Hey everyone, I'm new on forum. First think, sorry for my English but I try explain what happened. I have this problem since 3 months and I lost faith that something help with it.

I working on MacBook Pro Early 2011:

-15 inch

-procesor 2,2GHz Intel i7

-16GB RAM 1600mhz DDR3

-graphic ADM Radeon HD 6750M 1024 MB i Intel HD Graphics 3000 512MB

-Mac OS High Sierra 10.13.6

 I have MIDI Controller Pioneer DDJ RB and studio monitor Reloop ADM-5.I'm beginner so I play only at home. I have Rekordbox also (updated of course, but the old one also, because I tried find some solution). In the process is problem with sound, I mean some crackling and weird break, something like cable is not good connected. I am really tired because I trying find solution - I think like 50h front on laptop monitor. I check many many topics on this forum, check advises and try do something, but everything not worked. Every update's is done, drivers also. Setting of sound(preferences) and configuration of Midi also. Buffer size also check.I tried on another software like Virtual DJ, Traktor - and what... the same problem. Studio monitors, controller and cables checked - everything is ok with it. But something is wrong when connected with Macbook.

Studio monitors connect with DDJ RB by chinch, and DDJ RB usb cable with Macbook. On my previous laptop working very nice, now not.

Previous laptop:

-HP on Windowsie 8.1

-i5

-RAM 4GB

How can I solve this problem?

I tried reinstall rekordbox, drivers, everything. I watched many many videos on YT with hope that I find answer for my problem - unsuccessfully. Every advices in my case is for trash. Two days ago I bought usb hub with own power supply - problem still the same. I read articles about interface audio, necessary to make music. But not for rekordbox(right?). I hope that someone help me with it. 

Summarizing, this is things what I did:

-reinstall Rekordbox(check old one version also)

- when jumped on screen information about security- i did everything like I read on this forum from experts

-change cables

-bought hub usb

-wyłączenie aplikacji w tle

-change buffer size in rekordbox

- preferences sound and configuration midi

Rekordbox 4.5.0 (the old one version)

Rekordbox 5.4.0

Greetings