Noise in recordings

I have a MOTU and a couple of other digital audio computer interface units. As I turn up the recording level high enough to record to the computer, more and more noise is introduced to the recording. To record at -6db, silent sections will show/ record about -50 dB of noise onto the track. Enough that there is noticeable noise in the recording.
Is this something you experience. How much noise does your Digital Audio interface introduce to a track?
I would appreciate information on your experience and what Digital Audio Interface you use.

Bax sounds like you needs to do a couple of things. make sure in windows that the sample rates matches your project, that is if your using Win 10/7. Also at that point make sure your volume sliders in windows does not exceed 85, this will ensure you don’t overdrive the audio before or after you record.

Hope that helps Bax. :)

Thanks. It's Ben suggested and starting to look like it's the new electric meter the power company added. I added more grounding with a 10' cooper rod. I upgraded the power cleaner from .Furman.
Things have improvered. The strange thing to , I now get about a -70 dB at 75% volume on the MOTU channel. Better than the -50db I was getting. At -50, even my old ears could hear to noise from the MOTU when using nTrack and making no sounds.
I can't get any information as to what the dB reading floor should be from MOTU. However, I have an old Echo Audio unit that get the -50 dB floor so, . . . ? For instance, I'd love to know at the 85 % setting that you suggest if you could tell me what noise floor do you show?
Thanks for the suggestion.