DDJ-SZ Controller

I use Traktor Pro 2 on a 2017 MacBook Pro i7 16gb Ram, SSD.

Latency is as low as it will go.

The tracks do not jump or stutter.

I do have a crackling sound at high volume. I know the club sound system is ok as no other DJ has any issues. I have changed the XLR leads too.

I need to get rid of the crackling.

If the amps are on and I dont have the mic pluged into the lead I get a noise over the system till I plug it in?

Any idears?