About 4 times at start of gig I was getting audio dropouts, snow noise and even the track would stop playing, Luckly before gig testing all, I would reboot, change wall power source, eliminate power outlets and plug pioneer ddj sz directly in wall, still no fix, At the beginning of gig I would play hour long test tracks while setting up to test audio, this is when i notice i had a problem, rebooting would eventually fix to get through event with some dropouts, I couldnt duplicate at home untill i played those long hour or 90 minute mixes. so i saw the cpu couldnt handle that much data of long tracks, so after reinstalling serato dj, pioneer audio drivers, installing older vers of serato dj, change power sources , change latencey to every setting, nothing work to eliminate the problem, so then I used disk utility on macbook pro 2011 model with sierra OS, and found errors on disk, so in order to clean errors you have to run the disk utility by retarting and command R to fix errors on disk , on sierra it will not clean errors without rebooting and running the utility, so errors on all disk are fix I have 1TB main drive with serato dj pioneer drivers on and a 2nd driver i used for personal stuff, The main drive had errors. I also installed serato dj 1.9.1 and then 1.9.6 on top and left 1.9.1 stalled. I deleted pioneer drivers for SZ and installed latest audio driver. In serato dj i have a folder of about 50 mixes ranging from 30 min to 2hours, so after fixiing errors on disk and everything else i put the stress test on controller and software and problem gone, I used all 3 usb ports , punch in long tracks, turn on all effects, scratched, turn on web browser in backgroung played youtube in back ground, while punching in long tracks on all 4 decks, drops outs and white noise gone, When i had all 4 decks loaded with long tracks, I could see the serato cpu green meter go half way up but no red or orange lights like before, also playing youtube in back ground cpu meter went even higher with no problemalso ,I power down everything from scratch and did test on all 3 usb ports and couldnt duplicate problem, Buffer latency is at 10, when I moved it to a lower number 1 and 2 i could see it stressing but it kept playing and track didnt stop like before, Im leving latency at 10 seems to be ok there.

Ok I have early model 2011 macbook 2.3 GHz Intel Core i7 . 16gig memory,MD Radeon HD 6750M 1024 MB
Intel HD Graphics 3000 512 MB ,mac os sierra 10.12.5
1 tb crucial harddisk

serato dj 1.9.1 and 1.9.6 installed
latest pioneer ddj sz drivers
analyze all files for corrupt track.
tested 3 usb ports good,
change power cord for mac, no issues on either.
leaving Buffer latency an 10

So I probably think the errors on the disk were related to serato dj or pioneer controller drivers or software, because when changing serato dj vers. and audio drivers problem didnt go away not until i fix the disk errors then problem went away and I also thought maybe usb ports were bad but all 3 tested googd after disk fix, Dont know if its a combination off all i did but this is what i did and it worked for me.

By the way I had analize all tracks before gigs and found non bad even before problem but its good to this monthy, also I will scan for disk errors periodaclly now also. I will keep stressing the software and controller with long tracks before gigs also, I also notice 2 hours mixes took longer to load, and now they load instintly, I having been taking my Pioneer ddj sr as a backup just in case and never experience problem with same stress test, so go figure.