Hi, I'm using Sonar X1 producer Expanded and I just bought the Komplete audio 6. When I plug in my synthesizer to the input 3/4, set audio IN to Komplete 3/4 at the track and master output to Komplete mains out, I can't hear any sound from the main output 1/2 to my speakers. I can see the signal at the meter at Sonar and the input signal at the Komplete audio 6 but no signal out. Need help from all of you.

What driver mode are you using? I find ASIO to be the preferred driver mode.
Open the ASIO panel and make sure the KA6 interfaces are selected.
What NI driver version are you using for KA6? Make sure you're using V3.1.0.761, dated 12/18/2012
Do you have a web browser open while using Sonar? Close the web browser(s) and Sonar. Re-launch Sonar.
 
I'm use a KA6 using ASIO driver mode and can get round-trip latency as low as 1.3ms.
 

Oops, more like <10ms.
 
I was using ASIO4ALL when I posted the 1.3ms latency number.