@Spiritos, although different mic preamps vary in their ability to produce clean gain your question about it adding to the noise floor speaks more of ensuring a proper gain structure for your equipment. When this is achieved, the possible issue you mention would not occur. For example, with a relatively quiet vocalist placed 10 inches from the mic, singing into an SM57 plugged into a Triton Fethead, plugged into a TK Audio DP1 (mic preamp) and finally into the UR44 with its input level knob turned all the way down (effectively not using the UR44’s onboard preamp for gain) produces more than enough clean gain with no appreciable noise floor. I.e. suitable for an acoustic recording.
Check out https://www.youtube.com/watch?v=1h1ku5-C_3w as an example of a live recording I did for a UR44 review where gain structure is set up correctly to help ensure an almost imperceivable noise floor in spite of the noisy surroundings. All the mics used in this example are condensers and only the UR44 was used for gain, no other gain boosting equipment, but the principle is exactly the same
As a sidenote the UR44 appears to produce noticeable self noise once the input gain knob exceeds 50-60%. Nevertheless its an absolutely great unit for the price, especially if used with a Steinberg DAW thanks to the integrated functionality 