Low level noise/static with Intensity Shuttle Thunderbolt

I am running a Sony Handycam (HDR-CX580) in photo mode to avoid capture of the camera microphone. That is ran into the Blackmagic Design Intensity Shuttle Thunderport. The video is coming from HDMI and the audio is coming from the RCA on inputs on the Intensity, being sent from a Native Instruments Kontrol S8 DJ mixer. Even when there is no audio signal being sent to the Intensity, including unplugging the RCA ins, I am experiencing low-level noise/static.

Is there anything I am missing as to how to address this? I believe I've isolated the problem to the Intensity, as the camera mic is off (photo mode) and the RCAs are not causing it. Please let me know if any other information I could provide would help address this. Any help is greatly appreciated. Thanks!