Latency issue with Rave Partycast Aux In

Recently I brought a Pioneer FLX4 DJ controller and connected to Soundcore Rave partycast via Aux In cable. (RCA to 3.5mm jack)

Theres a small delay of the main output and headphone out. I have tested with JBL speakers and it works fine. No issues with the DJ controller. Same DJ controller works fine with Soundcore Motion +

Any solutions? Thank you !