Hi, how can i use headphones on the S4 when using an external soundcard (Komplete audio 6) ?
By default Traktor can't use multiple sound interfaces at the same time.
On mac you can use aggregated sound devices or on windows you can use ASIO4all. With that you can combine the s4 and audio 6 into a single virtual device. Choose that in Traktor and adjust the output routing after your needs.