Sound cutting in and out while playing

Thank you everyone for your input. I returned the (Non powered) Speaker and rented a different one to see if it would make a difference and it did. By the way, I do have the Power Rack going through Passive PA Speaker, not the other way around.

I ordered the Kemper cab so only using this rental speaker until I get it. The sound issue I have before is GONE! I guess it was the other speaker I bought that had the issue! Or it wasn't the right speaker for the Power Rack.