About sampling noise

Hi all, when I use the DT to sample the external synthesizer sound, even if I don’t play any notes, the DT will still record some white noise. I connected the L/R output of my DT and synthesizer with a pair of 1.5 meters cable. The threshold display from my DT shows a noise floor of around 18 to 20. If I don’t connect any cable on the external input of the DT, the noise floor display is not, but the recording is still a white noise, not the kind of soft analog noise which I imagined. Is this normal?

I just bought my DT few days, I made a stupid mistake when I installed it. I connected the EXT input jack of DT to the microphone input (1/4") phone plug of my Siemens LS-100 recorder, even worse was my LS-100 turned on the 48V phantom power, and when I found out, I quickly stopped the operation. Will this damage my DT?

2 posts were merged into an existing topic: Sampling empy inputs leads to white noise